The Full Wiki

Simple Mail Transfer Protocol: Wikis

  

Encyclopedia

From Wikipedia, the free encyclopedia

The Internet Protocol Suite
Application Layer
BGP · DHCP · DNS · FTP · GTP · HTTP · IMAP · IRC · Megaco · MGCP · NNTP · NTP · POP · RIP · RPC · RTP · RTSP · SDP · SIP · SMTP · SNMP · SOAP · SSH · Telnet · TLS/SSL · XMPP · (more)
Transport Layer
TCP · UDP · DCCP · SCTP · RSVP · ECN · OSPF · (more)
Internet Layer
IP (IPv4, IPv6) · ICMP · ICMPv6 · IGMP · IPsec · (more)
Link Layer
ARP/InARP · NDP · Tunnels (L2TP) · PPP · Media Access Control (Ethernet, DSL, ISDN, FDDI) · (more)
.Simple Mail Transfer Protocol (SMTP) is an Internet standard for electronic mail (e-mail) transmission across Internet Protocol (IP) networks.^ An email server exchanges emails with other servers using Simple Mail Transfer Protocol (SMTP).
  • Email SMTP: Providers and Solutions | Business.com 11 January 2010 15:19 UTC www.business.com [Source type: News]

^ SNMP Simple network monitoring protocol .

^ SMTP (Simple Mail Transfer Protocol) is a TCP/IP protocol used to send and receive e-mail.
  • Brief History of the Internet: Common Internet Protocols 11 January 2010 15:19 UTC www.adobe.com [Source type: General]

.SMTP was first defined in RFC 821 (STD 15) (1982)[1], and last updated by RFC 5321 (2008)[2] which includes the extended SMTP (ESMTP) additions, and is the protocol in widespread use today.^ The specifications for the SMTP are published in RFC 821 .
  • Simple Mail Transfer Protocol 11 January 2010 15:19 UTC it.toolbox.com [Source type: FILTERED WITH BAYES]

^ The most recent update is referred to as RFC 5321 (2008) In wide-spread use, also commonly called and supported as so-called extended SMTP or, (ESMTP).
  • MCTS - Exam 70-536: Simple Mail Transfer Protocol 11 January 2010 15:19 UTC mcts-exam-terms.com [Source type: Reference]

^ The protocol used today is also known as ES...
  • Questions about Simple Mail Transfer Protocol - Ask.com 11 January 2010 15:19 UTC www.ask.com [Source type: General]
  • Questions about SMTP Protocol - Ask.com 11 January 2010 15:19 UTC www.ask.com [Source type: General]

SMTP is specified for outgoing mail transport and uses TCP port 25.
.While electronic mail servers and other mail transfer agents use SMTP to send and receive mail messages, user-level client mail applications typically only use SMTP for sending messages to a mail server for relaying.^ Typically, this is done by contacting the SMTP port (port 25) on a mail server.
  • The Simple Mail Transfer Protocol is a standard for mail transport 11 January 2010 15:19 UTC www.web-articles.info [Source type: FILTERED WITH BAYES]

^ An email server exchanges emails with other servers using Simple Mail Transfer Protocol (SMTP).
  • Email SMTP: Providers and Solutions | Business.com 11 January 2010 15:19 UTC www.business.com [Source type: News]

^ SMTP (Simple Mail Transfer Protocol) is a TCP/IP protocol used to send and receive e-mail.
  • Brief History of the Internet: Common Internet Protocols 11 January 2010 15:19 UTC www.adobe.com [Source type: General]

.For receiving messages, client applications usually use either the Post Office Protocol (POP) or the Internet Message Access Protocol (IMAP) to access their mail box accounts on a mail server.^ This protocol is used by a client which wishes to interact with mail stored on a server.
  • NetA2008-Lecture 11: Wednesday February, 2008: 20 Mail Protocols 11 January 2010 15:19 UTC spectral.mscs.mu.edu [Source type: Reference]

^ Internet Message Access Protocol ( IMAP ) Industry standard email retrieval and storage protocol.
  • http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/glossary/index.html 11 January 2010 15:19 UTC www.redhat.com [Source type: Reference]

^ IMAP mail server .

Contents

History

.Various forms of one-to-one electronic messaging were used in the 1960s.^ It is therefore usually used with one of two other protocols -- POP3 or Internet Message Access Protocol (IMAP) -- that lets the user access messages in a server mailbox and download them periodically from the server.
  • InfoChannel > Customer Care > FAQ's > Other FAQ's 11 January 2010 15:19 UTC www.infochan.com [Source type: General]

^ Most e-mail systems that send mail over the Internet use SMTP to send messages from one server to another; the messages can then be retrieved with an e-mail client using either POP or IMAP. In addition, SMTP is generally used to send messages from a...
  • Download Smtp Software - Downloads Free Smtp : Xentrik 19 September 2009 6:31 UTC www.xentrik.net [Source type: General]

^ It's usually used with one of two other protocols, POP3 or Internet Message Access Protocol, that let the user save messages in a server mailbox and download them from the server.
  • Email Setup Instructions for Outlook Express 11 January 2010 15:19 UTC www.topshome.net [Source type: General]

.People communicated with one another using systems developed for specific mainframe computers.^ An operating system used on workstations and computers.
  • Cherry Media - How does hosting work? 11 January 2010 15:19 UTC cherrymedia.com [Source type: Reference]

^ Most e-mail systems that send mail over the Internet use SMTP to send messages from one server to another; the messages can then be retrieved with an e-mail client using either POP or IMAP. In addition, SMTP is generally used to send messages from a...
  • Download Smtp Software - Downloads Free Smtp : Xentrik 19 September 2009 6:31 UTC www.xentrik.net [Source type: General]

^ When it comes to enabling communication  this is  popular and proven  mechanism, for sending files, reports and notifications email is a useful tool for developers.
  • MCTS - Exam 70-536: Simple Mail Transfer Protocol 11 January 2010 15:19 UTC mcts-exam-terms.com [Source type: Reference]

.As more computers were interconnected, especially in the US Government's ARPANET, standards were developed to allow users using different systems to be able to e-mail one another.^ Some people use more than one desktop computer to read mail.
  • LAN Mail Protocols Summary (Most recent update: 3/13/99) 11 January 2010 15:19 UTC www.faqs.org [Source type: FILTERED WITH BAYES]

^ It is also common to allow a user to optionally "forward" her mail to one or more alternate addresses.
  • draft-moore-rfc1891bis-02 - Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs) 11 January 2010 15:19 UTC tools.ietf.org [Source type: Reference]

^ An operating system used on workstations and computers.
  • Cherry Media - How does hosting work? 11 January 2010 15:19 UTC cherrymedia.com [Source type: Reference]

.SMTP grew out of these standards developed during the 1970s.^ Related to these developments is the relationship between TCP/IP and the OSI standards -- and the uncertain future of these internationally recognized standards.
  • Internet Protocol (TCP/IP) Training 11 January 2010 15:19 UTC www.telematix.com [Source type: Reference]

^ The IETF develops these standards with the goal of co-ordinating the evolution of the Internet protocols; this co-ordination has become quite important as the Internet protocols are increasingly in general commercial use.
  • rfc1500 - INTERNET OFFICIAL PROTOCOL STANDARDS 11 January 2010 15:19 UTC aurora.rg.iupui.edu [Source type: Reference]

^ Internet Architecture Board [Page 6] RFC 1500 Internet Standards August 1993 Note that these MIL-STD are now somewhat out of date.
  • rfc1500 - INTERNET OFFICIAL PROTOCOL STANDARDS 11 January 2010 15:19 UTC aurora.rg.iupui.edu [Source type: Reference]

.SMTP can trace its roots to two implementations described in 1971, the Mail Box Protocol, which has been disputed to actually have been implemented,[3] but is discussed in RFC 196 and other RFCs, and the SNDMSG program, which, according to RFC 2235, Ray Tomlinson of BBN "invents" for TENEX computers the sending of mail across the ARPANET.[4][5][6] Fewer than 50 hosts were connected to the ARPANET at this time.^ SMTP is a protocol for sending e-mail across the internet.
  • MOREnet - kinetic Resources 11 January 2010 15:19 UTC kinetic.more.net [Source type: Reference]

^ SMTP is a client/server protocol in which an e-mail client connects to the server to transfer e-mail messages.

^ The most popular protocol for sending e-mail is SMTP and a popular protocol for receiving it is POP3.
  • About Web Service On debonne.net 11 January 2010 15:19 UTC www.debonne.net [Source type: General]

[7]
.Further implementations include FTP Mail [8] and Mail Protocol, both from 1973.[9] The work continued throughout the 1970s, until the ARPANET converted into the modern Internet around 1980. Jon Postel then proposed a Mail Transfer Protocol in 1980 that began to remove the mail's reliance on FTP.^ Simple Mail Transfer Protocol commands .
  • Simple Mail Transfer Protocol commands 11 January 2010 15:19 UTC www.onlinehowto.net [Source type: Reference]

^ The simple Transfer protocol of Mail.
  • SMTP protocol. Adjustment of mail. 19 September 2009 6:31 UTC www.zemskov.net [Source type: FILTERED WITH BAYES]

^ FTP is a protocol that supports the transfer of files.
  • EIW Fall 2000 Lecture Notes - Internet Application Protocols 11 January 2010 15:19 UTC www.cs.rpi.edu [Source type: FILTERED WITH BAYES]

[10] .SMTP was published as RFC 821 in August 1982, also by Postel.^ The specifications for the SMTP are published in RFC 821 .
  • Simple Mail Transfer Protocol 11 January 2010 15:19 UTC it.toolbox.com [Source type: FILTERED WITH BAYES]

^ SMTP was first defined in RFC 821 ...
  • SMTP - Search Results - MSN Encarta 19 September 2009 6:31 UTC encarta.msn.com [Source type: General]

^ MTAs implement SMTP (RFC 821).
  • Extended Simple Mail Transfer Protocol (ESMTP) Accounting in Store and Forward Fax  [Cisco IOS Software Releases 12.0 T] - Cisco Systems 11 January 2010 15:19 UTC www.cisco.com [Source type: Reference]

.The SMTP standard was developed around the same time as Usenet, a one-to-many communication network with some similarities.^ This is the standard model for network communication developed by International Organization for Standardization (ISO).
  • Understanding Network Protocols 11 January 2010 15:19 UTC www.tech-faq.com [Source type: Reference]

^ Consider consumer electronic devices that communicate over standard Ethernet networks.

^ The notes discuss many aspects of computing and computer communication focusing in networking protocols, procedures, programs, and concepts, but also including meeting notes, opinion, and sometimes humor.
  • Protocols - Acronyms List 11 January 2010 15:19 UTC www.protocols.com [Source type: Reference]

.SMTP became widely used in the early 1980s.^ SMTP started becoming widely used in the early 1980s.
  • Soft32.com Help 11 January 2010 15:19 UTC help.soft32.com [Source type: General]

^ SMTP uses a style of asymmetric request-response protocol that was popular in the early 1980s, but still seen occasionally, most often in mail protocols.
  • FRII - Customer Support Email: Protocol: What is SMTP (Simple Mail Transfer Protocol)? 11 January 2010 15:19 UTC frii.com [Source type: Reference]

^ SMTP is widely used as a notification mechanism for anomalous events.

.At the time, it was a complement to Unix to Unix Copy Program (UUCP) mail, which was better suited to handle e-mail transfers between machines that were intermittently connected.^ At the time, it was a complement to UUCP (Unix to Unix CoPy) which was better suited to handle e-mail transfers between machines that were intermittently connected.
  • Soft32.com Help 11 January 2010 15:19 UTC help.soft32.com [Source type: General]

^ Most e-mail systems that send mail over the Internet use SMTP to send messages from one server to another; the messages can then be retrieved with an e-mail client using either POP or IMAP. UUCP Unix to Unix Copy Protocol.
  • Protocols... - Powered by netCORE Solutions Pvt Ltd. 11 January 2010 15:19 UTC support.netcore.co.in [Source type: General]

^ This is the protocol that actually transfers mail from sender to receiver, between endpoints of the message and/or forwarding agents.
  • NetA2008-Lecture 11: Wednesday February, 2008: 20 Mail Protocols 11 January 2010 15:19 UTC spectral.mscs.mu.edu [Source type: Reference]

.SMTP, on the other hand, works best when both the sending and receiving machines are connected to the network all the time.^ SMTP, on the other hand, works best when both the sending and receiving machines are connected to the network all the time.
  • Soft32.com Help 11 January 2010 15:19 UTC help.soft32.com [Source type: General]

^ The SMTP client time limit for sending the SMTP ".", and for receiving the server response.
  • Package Documentation 19 September 2009 6:31 UTC cpplus.psoft.net [Source type: FILTERED WITH BAYES]

^ At the time of this writing, MUAs such as Mozilla Mail, Evolution, Balsa, Opera M2, Outlook Express, Netscape Mail, KMail, and Sylpheed all supported sending SMTP mail with TLS/SSL and authenticating with username and password.
  • Essential Internet Protocols - SMTP 19 September 2009 6:31 UTC www.vanemery.com [Source type: FILTERED WITH BAYES]

.Both use a store and forward mechanism and are examples of push technology.^ In situations where e-mail is stored on a remote server and then forwarded to the user (where a home user connects to the Internet through an ISP and downloads e-mail periodically, for example), POP3 or IMAP protocols are often used also.
  • Viruslist.com - SMTP [Simple Mail Transfer Protocol] 11 January 2010 15:19 UTC www.viruslist.com [Source type: FILTERED WITH BAYES]

^ All of the mechanisms specified in this document are described in both prose and an augmented Backus-Naur Form (BNF) similar to that used by RFC 822 [7] .
  • Hypertext Transfer Protocol -- HTTP/1.0 11 January 2010 15:19 UTC www.w3.org [Source type: Reference]

^ Messages between local users are stored on the eMail Station server without being transmitted to the ISP; Messages to and from users on the Internet are forwarded through the ISP, using SMTP for both sending and receiving.
  • Intel� InBusiness� eMail Station - Mail Delivery Method A: Simple Mail Transfer Protocol (SMTP) 11 January 2010 15:19 UTC www.intel.com [Source type: Reference]

.Though Usenet's newsgroups are still propagated with UUCP between servers,[11] UUCP mail has virtually disappeared[12] along with the "bang paths" it used as message routing headers.^ Use server SMTP to send e-mail messages.
  • SMTP downloads on CNET 19 September 2009 6:31 UTC www.cnet.com [Source type: General]

^ SMTP is the protocol used by mail servers to exchange email messages.
  • EIW Fall 2000 Lecture Notes - Internet Application Protocols 11 January 2010 15:19 UTC www.cs.rpi.edu [Source type: FILTERED WITH BAYES]

^ Example 822 Mail Message Header: .
  • Lesson 26: E-mail, SMTP, and MIME Types 11 January 2010 15:19 UTC www.cis.njit.edu [Source type: Reference]

.The article about sender rewriting contains technical background info about the early SMTP history and source routing before RFC 1123.^ The article about sender rewriting contains technical background info about the early SMTP history and source routing before RFC 1123 (1989, obsoleted by RFC 2821).
  • Soft32.com Help 11 January 2010 15:19 UTC help.soft32.com [Source type: General]

^ SMTP is also independent of operating systems, which means each system can use its own style of storing mail without worrying about how senders of messages store their mail.
  • The Simple Mail Transfer Protocol is a standard for mail transport 11 January 2010 15:19 UTC www.web-articles.info [Source type: FILTERED WITH BAYES]

^ Each IP datagram includes addressing information, information for use in routing the datagram, and a data portion that contains the message the source wants to transmit to the destination.
  • Jan Axelson's Lakeview Research 11 January 2010 15:19 UTC www.lvr.com [Source type: Reference]

.Sendmail was one of the first (if not the first) mail transfer agents to implement SMTP.[citation needed] Some other popular SMTP server programs include Postfix, qmail, Novell GroupWise, Exim, Novell NetMail, Microsoft Exchange Server, Sun Java System Messaging Server.^ Some other popular SMTP server programs include Postfix, qmail, Novell GroupWise, Exim, Novell NetMail and Microsoft Exchange Server.
  • Soft32.com Help 11 January 2010 15:19 UTC help.soft32.com [Source type: General]

^ An email server exchanges emails with other servers using Simple Mail Transfer Protocol (SMTP).
  • Simple Mail Transfer Protocol (SMTP) Information | Business.com 11 January 2010 15:19 UTC www.business.com [Source type: General]

^ Messaging Application Programming Interface (MAPI) is used with Outlook in conjunction with a Microsoft Exchange Server mail server.
  • Crabby demystifies e-mail protocols - Outlook - Microsoft Office Online 11 January 2010 15:19 UTC office.microsoft.com [Source type: General]
  • Crabby demystifies e-mail protocols - Help and How-to - Microsoft Office Online 11 January 2010 15:19 UTC office.microsoft.com [Source type: General]

.Message submission (RFC 2476) and SMTP-AUTH (RFC 2554) were introduced in 1998 and 1999, both describing new trends in e-mail delivery.^ SMTP -AUTH is defined in RFC 2554.
  • General Mail System Terminology [Joyent Wiki] 11 January 2010 15:19 UTC wiki.joyent.com [Source type: Reference]

^ RFC 4409 - Message Submission for Mail.
  • Infos about Internet Mail and News 11 January 2010 15:19 UTC mark.doll.name [Source type: Reference]

^ The SMTP specification is described in RFC 821.
  • What is SMTP? - Definition from Whatis.com - see also: Simple Mail Transfer Protocol 19 September 2009 6:31 UTC searchexchange.techtarget.com [Source type: Reference]

.Originally, SMTP servers were typically internal to an organization, receiving mail for the organization from the outside, and relaying messages from the organization to the outside.^ Typically, this is done by contacting the SMTP port (port 25) on a mail server.
  • The Simple Mail Transfer Protocol is a standard for mail transport 11 January 2010 15:19 UTC www.web-articles.info [Source type: FILTERED WITH BAYES]

^ The mail is typically removed from the server.
  • InformIT: Security Review of Protocols: The Upper Layers > Messaging 11 January 2010 15:19 UTC www.informit.com [Source type: General]

^ Use server SMTP to send e-mail messages.
  • SMTP downloads on CNET 19 September 2009 6:31 UTC www.cnet.com [Source type: General]

.But as time went on, SMTP servers (Mail transfer agents), in practice, were expanding their roles to become message submission agents for Mail user agents, some of which were now relaying mail from the outside of an organization.^ Use server SMTP to send e-mail messages.
  • SMTP news and downloads on CNET 19 September 2009 6:31 UTC brighthand.com.com [Source type: General]

^ SMTP is a client/server protocol in which an e-mail client connects to the server to transfer e-mail messages.

^ SMTP is the protocol used by mail servers to exchange email messages.
  • EIW Fall 2000 Lecture Notes - Internet Application Protocols 11 January 2010 15:19 UTC www.cs.rpi.edu [Source type: FILTERED WITH BAYES]

(e.g. .A company executive wishes to send e-mail while on a trip using the corporate SMTP server.^ Use server SMTP to send e-mail messages.
  • SMTP downloads on CNET 19 September 2009 6:31 UTC www.cnet.com [Source type: General]

^ SMTP is used for transmission of e-mails.

^ You can send mail from any mail client that is complaint with SMTP protocol using this server.
  • SMTP Resources | ZDNet 19 September 2009 6:31 UTC updates.zdnet.com [Source type: General]

) .This issue, a consequence of the rapid expansion and popularity of the World Wide Web, meant that the SMTP protocol had to include specific rules and methods for relaying mail and authenticating users to prevent abuses such as unsolicited e-mail (spam) relaying.^ SMTP Simple mail transfer protocol .

^ See World Wide Web for the common http protocol .
  • Protocol definition by Babylon's free dictionary 11 January 2010 15:19 UTC dictionary.babylon.com [Source type: Reference]

^ SMTP – simple mail transfer protocol.

.As this protocol started out purely ASCII text-based, it did not deal well with binary files.^ Signatures are usually ASCII text files.

^ Since this protocol started out as purely ASCII text-based, it did not deal well with binary files.
  • Soft32.com Help 11 January 2010 15:19 UTC help.soft32.com [Source type: General]

^ FTP uses TCP protocol for communication, and capable of transferring both binary files and text files.  Some popular FTP clients include FileZilla, and cuteFTP. .
  • Network+ Tutorials - Protocols and Standards - Protocols 11 January 2010 15:19 UTC www.simulationexams.com [Source type: Reference]

.Standards such as Multipurpose Internet Mail Extensions (MIME) were developed to encode binary files for transfer through SMTP. Mail transfer agents (MTAs) developed after Sendmail also tended to be implemented 8-bit-clean, so that the alternate "just send eight" strategy could be used to transmit arbitrary text data (in any 8-bit ASCII-like character encoding) via SMTP. 8-bit-clean MTAs today tend to support the 8BITMIME extension, permitting binary files to be transmitted almost as easily as plain text.^ MIME Overview Discusses the need for and the implementation of Multipurpose Internet Mail Extensions.
  • Email Beginnings 11 January 2010 15:19 UTC www.dart.com [Source type: FILTERED WITH BAYES]
  • SMTP Protocol Overview 11 January 2010 15:19 UTC www.dart.com [Source type: FILTERED WITH BAYES]

^ Support 8BITMIME and BINARYMIME which will optimize performance for binary data.
  • Messaging Protocols for HF Radio 11 January 2010 15:19 UTC www.isode.com [Source type: FILTERED WITH BAYES]

^ SMTP is a protocol for sending e-mail across the internet.
  • MOREnet - kinetic Resources 11 January 2010 15:19 UTC kinetic.more.net [Source type: Reference]

Mail processing model

The overall flow for message creation, mail transport and delivery may be illustrated as follows:
sending MUA → MSA → sending MTA → receiving MTA → MDA → Mailstore for retrieval by MUA
.E-mail is submitted from a mail client (MUA, message user agent) to a mail server (MSA, message submission agent) using SMTP usually.^ Use server SMTP to send e-mail messages.
  • SMTP downloads on CNET 19 September 2009 6:31 UTC www.cnet.com [Source type: General]

^ SMTP is a client/server protocol in which an e-mail client connects to the server to transfer e-mail messages.

^ You can send mail from any mail client that is complaint with SMTP protocol using this server.
  • SMTP Resources | ZDNet 19 September 2009 6:31 UTC updates.zdnet.com [Source type: General]

.From there, the MSA delivers the mail to an MTA, often running on the same machine.^ The chat sequence used by Sendmail to deliver mail can be shown by running sendmail manually at the command line with a "-v" parameter.
  • SMTP Commands 19 September 2009 6:31 UTC www.the-welters.com [Source type: FILTERED WITH BAYES]

^ SMTP also can provide notification for e-mails that are not delivered (via MTAs along the way).

^ If the remote machine offers more than one of these services, there is server software running for each of them, and the protocol determines which one is going to handle your requests.
  • Christ Church -- FAQ: What are protocols? 11 January 2010 15:19 UTC www.christchurchsummit.org [Source type: FILTERED WITH BAYES]

.A message may be directly submitted to an MTA: TCP port 587 is typically used for submission to MSAs (thence to MTAs), while TCP port 25 must be used for transferring to MTAs.^ SMTP uses TCP port 25.
  • Soft32.com Help 11 January 2010 15:19 UTC help.soft32.com [Source type: General]

^ Yahoo Mail also supports standard SMTP. To setup your application for working with your Yahoo account, you need to use the Yahoo Outgoing SMTP Server- smtp.mail.yahoo.com (Port 25).
  • Support - FAQ - Simple Com Tools 11 January 2010 15:19 UTC www.simplecomtools.com [Source type: FILTERED WITH BAYES]

^ In other words, users typically use a program that utilizes SMTP for sending e-mail and either POP3 or IMAP for receiving messages that have been stored for them at their local server.
  • InfoChannel > Customer Care > FAQ's > Other FAQ's 11 January 2010 15:19 UTC www.infochan.com [Source type: General]

.The MTA looks up the destination's mail exchanger record (MX record) in the Domain name system (DNS), and relays the mail to a server on record via TCP port 25 and SMTP. (The article on MX record discusses many factors in determining which server the sending MTA connects to.^ The port number of the SMTP server to connect to.
  • Class: Net::SMTP 19 September 2009 6:31 UTC www.ruby-doc.org [Source type: Reference]

^ This is the domain name which you are on (the host to send mail from).
  • Class: Net::SMTP 19 September 2009 6:31 UTC www.ruby-doc.org [Source type: Reference]

^ Use server SMTP to send e-mail messages.
  • SMTP downloads on CNET 19 September 2009 6:31 UTC www.cnet.com [Source type: General]

) .Once the receiving MTA accepts the incoming message, it is delivered via a mail delivery agent (MDA) to a server which is designated for local mail delivery.^ The MTA that sends an e-mail message.
  • Selected MARID-Related Terms and Acronyms 11 January 2010 15:19 UTC www.technoids.org [Source type: Reference]

^ Failure of a conforming MTA to deliver a message .
  • draft-moore-rfc1891bis-02 - Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs) 11 January 2010 15:19 UTC tools.ietf.org [Source type: Reference]

^ Local delivery of messages .
  • draft-moore-rfc1891bis-02 - Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs) 11 January 2010 15:19 UTC tools.ietf.org [Source type: Reference]

.The MDA either delivers the mail directly to storage, or forwards it over a network using either SMTP or the Local Mail Transfer Protocol (LMTP), a derivative of ESMTP designed for this purpose.^ An email server exchanges emails with other servers using Simple Mail Transfer Protocol (SMTP).
  • Simple Mail Transfer Protocol (SMTP) Information | Business.com 11 January 2010 15:19 UTC www.business.com [Source type: General]
  • Email SMTP: Providers and Solutions | Business.com 11 January 2010 15:19 UTC www.business.com [Source type: News]

^ SMTP (Simple Mail Transfer Protocol) is a TCP/IP protocol used to send and receive e-mail.
  • Brief History of the Internet: Common Internet Protocols 11 January 2010 15:19 UTC www.adobe.com [Source type: General]

^ SMTP is a client/server protocol in which an e-mail client connects to the server to transfer e-mail messages.

.Once delivered to the local mail server, the mail is stored for batch retrieval by authenticated mail clients (MUAs).^ This protocol is used by a client which wishes to interact with mail stored on a server.
  • NetA2008-Lecture 11: Wednesday February, 2008: 20 Mail Protocols 11 January 2010 15:19 UTC spectral.mscs.mu.edu [Source type: Reference]

^ A protocol used to retrieve e-mail from a mail server.

^ Authenticate the client to the server.
  • Simple Mail Transfer Protocol 11 January 2010 15:19 UTC www.catalyst.com [Source type: FILTERED WITH BAYES]

.Mail is retrieved by end-user applications, the email clients, using Internet Message Access Protocol (IMAP), a protocol that both facilitates access to mail and manages stored mail, or the Post Office Protocol (POP) which typically uses the traditional mbox mail file format.^ This protocol is used by a client which wishes to interact with mail stored on a server.
  • NetA2008-Lecture 11: Wednesday February, 2008: 20 Mail Protocols 11 January 2010 15:19 UTC spectral.mscs.mu.edu [Source type: Reference]

^ Internet Message Access Protocol ( IMAP ) Industry standard email retrieval and storage protocol.
  • http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/glossary/index.html 11 January 2010 15:19 UTC www.redhat.com [Source type: Reference]

^ In the split- MUA model, POP or IMAP is used to access delivered messages.
  • Essential Internet Protocols - SMTP 19 September 2009 6:31 UTC www.vanemery.com [Source type: FILTERED WITH BAYES]

.Webmail clients may use either method, but the retrieval protocol is often not a formal standard.^ A protocol used to retrieve e-mail from a mail server.

^ A standard protocol used to retrieve e-mail stored on a mail server.
  • Linksys.com – Learning Center/Glossary 11 January 2010 15:19 UTC www-in.linksys.com [Source type: Reference]

^ A protocol that client e-mail applications use to retrieve mail from a mail server.
  • E-mail Inspection Engine  [Cisco IOS Software Releases 12.3 T] - Cisco Systems 11 January 2010 15:19 UTC cio.cisco.com [Source type: Reference]

.Some local mail servers and MUAs are capable of either push or pull mail retrieval.^ Some error occurmiles in the mail server.
  • Sending Mail (SMTP) 19 September 2009 6:31 UTC www.cs.cf.ac.uk [Source type: FILTERED WITH BAYES]

^ Mail access protocol: retrieval from server .
  • ftp: the file transfer protocol 11 January 2010 15:19 UTC homepages.udayton.edu [Source type: Reference]

^ In other words, users typically use a program that utilizes SMTP for sending e-mail and either POP3 or IMAP for receiving messages that have been stored for them at their local server.
  • InfoChannel > Customer Care > FAQ's > Other FAQ's 11 January 2010 15:19 UTC www.infochan.com [Source type: General]

. SMTP defines message transport, not the message content.^ Contents of the DSN A DSN is transmitted as a MIME message with a top-level content-type of multipart/report (as defined in [ 5 ]).
  • draft-moore-rfc1891bis-02 - Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs) 11 January 2010 15:19 UTC tools.ietf.org [Source type: Reference]

^ RFC 822 defines the format of SMTP messages.
  • SMTP (Simple Mail Transfer Protocol) 11 January 2010 15:19 UTC www.networkworld.com [Source type: General]

^ The maximal number of recipients per delivery via the smtp message delivery transport.
  • Package Documentation 19 September 2009 6:31 UTC cpplus.psoft.net [Source type: FILTERED WITH BAYES]

.Thus, it defines the mail envelope and its parameters, such as the envelope sender, but not the header or the body of the message itself.^ The body of the fax-mail message is sent.
  • Extended Simple Mail Transfer Protocol (ESMTP) Accounting in Store and Forward Fax  [Cisco IOS Software Releases 12.0 T] - Cisco Systems 11 January 2010 15:19 UTC www.cisco.com [Source type: Reference]

^ The subject and message body of the e-mail notification is user defined.
  • Simple Failover - Features 11 January 2010 15:19 UTC www.simplefailover.com [Source type: General]
  • Simple Failover - The simple yet powerful software failover solution 11 January 2010 15:19 UTC www.bestshareware.net [Source type: General]

^ C: This is a test message with 5 headers and 4 lines in the body.
  • CCIE SECApplication Protocols - XMind - Social Brainstorming and Mind Mapping 11 January 2010 15:19 UTC www.xmind.net [Source type: Reference]

.STD 10 and RFC 5321 define SMTP (the envelope), while STD 11 and RFC 5322 define the message (header and body), formally referred to as the Internet Message Format.^ Standard for the Format of Text Messages (STD 11) .
  • TCPware V5.7 User's Guide AppA.htm 11 January 2010 15:19 UTC www.process.com [Source type: Reference]

^ RFC 822 defines the format of SMTP messages.
  • SMTP (Simple Mail Transfer Protocol) 11 January 2010 15:19 UTC www.networkworld.com [Source type: General]

^ RFC 2822 “Internet Message Format”, updates to the email message format.
  • smtplib – Simple Mail Transfer Protocol client - Python Module of the Week 11 January 2010 15:19 UTC www.doughellmann.com [Source type: FILTERED WITH BAYES]

Protocol overview

.SMTP is a text-based protocol, in which a mail sender communicates with a mail receiver by issuing command strings and supplying necessary data over a reliable ordered data stream channel, typically a Transmission Control Protocol (TCP) connection.^ "Once the transmission channel is established, the SMTP-sender sends a MAIL command indicating the sender of the mail.
  • USB Computer Science - CSE103, Fall 2001 -- Protocols 11 January 2010 15:19 UTC www.cs.sunysb.edu [Source type: Reference]

^ SMTP is a client/server protocol in which an e-mail client connects to the server to transfer e-mail messages.

^ Connection Establishment The SMTP transmission channel is a TCP connection established between the sender process port U and the receiver process port L. This single full duplex connection is used as the transmission channel.
  • Internet Request for Comments (RFC) 821: Simple Mail Transfer Protocol (Part 2) 11 January 2010 15:19 UTC www.gssnet.com [Source type: FILTERED WITH BAYES]

[2] .An SMTP session consists of commands originated by the SMTP client and corresponding responses from the SMTP server by which the session is opened, session parameters are exchanged, the recipients are specified and possibly verified, and the message is transmitted, before the session is closed.^ SMTP commands are generated by the SMTP client and sent to the SMTP server .
  • Simple Mail Transfer Protocol [RFC-Ref] 11 January 2010 15:19 UTC rfc-ref.org [Source type: Reference]

^ SMTP is a client/server protocol in which an e-mail client connects to the server to transfer e-mail messages.

^ SMTP is the protocol used by mail servers to exchange email messages.
  • EIW Fall 2000 Lecture Notes - Internet Application Protocols 11 January 2010 15:19 UTC www.cs.rpi.edu [Source type: FILTERED WITH BAYES]

.The originating host is either an end-user's email client, functionally identified as a mail user agent (MUA), or a relay server's mail transfer agent (MTA).^ MTA ) See mail client .
  • http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/glossary/index.html 11 January 2010 15:19 UTC www.redhat.com [Source type: Reference]

^ SMTP is a client/server protocol in which an e-mail client connects to the server to transfer e-mail messages.

^ The function will return the name of the servers responsible for accepting mail for that user.
  • Simple Mail Transfer Protocol 11 January 2010 15:19 UTC www.catalyst.com [Source type: FILTERED WITH BAYES]

.SMTP was designed as an electronic mail transport and delivery protocol, and as such it is used between SMTP systems that are operational at all times.^ SMTP is the protocol used by mail servers to exchange email messages.
  • EIW Fall 2000 Lecture Notes - Internet Application Protocols 11 January 2010 15:19 UTC www.cs.rpi.edu [Source type: FILTERED WITH BAYES]

^ LMTP protocol for transporting mail into such systems.
  • Protocol: SMTP ( Simple Mail Transfer Protocol ) 11 January 2010 15:19 UTC www.protocolbase.net [Source type: Reference]

^ In this section, we deal with mail transport protocols.
  • InformIT: Security Review of Protocols: The Upper Layers > Messaging 11 January 2010 15:19 UTC www.informit.com [Source type: General]

.However, it has capabilities for use as a mail submission protocol[2] for email clients (split user-agent) that do not have the capability to operate as MTA. Such agents are also called message submission agents (MSA),[13] sometimes also referred to as mail submission agents.^ This protocol is used by a client which wishes to interact with mail stored on a server.
  • NetA2008-Lecture 11: Wednesday February, 2008: 20 Mail Protocols 11 January 2010 15:19 UTC spectral.mscs.mu.edu [Source type: Reference]

^ SMTP is a client/server protocol in which an e-mail client connects to the server to transfer e-mail messages.

^ SMTP is the protocol used by mail servers to exchange email messages.
  • EIW Fall 2000 Lecture Notes - Internet Application Protocols 11 January 2010 15:19 UTC www.cs.rpi.edu [Source type: FILTERED WITH BAYES]

.They are typically end-user applications and send all messages through a smart relay server, often called the outgoing mail server, which is specified in the programs' configuration.^ The mail is typically removed from the server.
  • InformIT: Security Review of Protocols: The Upper Layers > Messaging 11 January 2010 15:19 UTC www.informit.com [Source type: General]

^ Use server SMTP to send e-mail messages.
  • SMTP downloads on CNET 19 September 2009 6:31 UTC www.cnet.com [Source type: General]

^ The MTA that sends an e-mail message.
  • Selected MARID-Related Terms and Acronyms 11 January 2010 15:19 UTC www.technoids.org [Source type: Reference]

.A mail transfer agent, incorporated either in the e-mail client directly or in the relay server, typically determines the destination SMTP server by querying the Domain Name System for the mail exchanger (MX record) of each recipient's domain name.^ Typically, this is done by contacting the SMTP port (port 25) on a mail server.
  • The Simple Mail Transfer Protocol is a standard for mail transport 11 January 2010 15:19 UTC www.web-articles.info [Source type: FILTERED WITH BAYES]

^ Domain Name System label .
  • Search | Novell User Communities 11 January 2010 15:19 UTC www.novell.com [Source type: Reference]

^ The mail is typically removed from the server.
  • InformIT: Security Review of Protocols: The Upper Layers > Messaging 11 January 2010 15:19 UTC www.informit.com [Source type: General]

.Conformant MTAs fall back to a simple address lookup (A record) of the domain name when no mail exchanger is available.^ I mean the address / domain name.
  • Hotmail pop3 & SMTP config : hotmail, pop3, server 19 September 2009 6:31 UTC www.experts-exchange.com [Source type: FILTERED WITH BAYES]

^ If there is no mail exchange record for a domain, then the domain name itself is used.
  • Simple Mail Transfer Protocol 11 January 2010 15:19 UTC www.catalyst.com [Source type: FILTERED WITH BAYES]

^ NO *NO, *SAME, *YES Incoming mail server address Mail domain name .
  • Frequently Asked Questions 11 January 2010 15:19 UTC www.easy400.net [Source type: FILTERED WITH BAYES]

.In some cases an SMTP client, even a server, may also be configured to use a smart host for delivery.^ An ECHO client and server using TCP .
  • Simple Mail Transfer Protocol (SMTP) 11 January 2010 15:19 UTC www.powerbasic.com [Source type: News]

^ SMTP: delivery/storage to receivers server .
  • ftp: the file transfer protocol 11 January 2010 15:19 UTC homepages.udayton.edu [Source type: Reference]

^ Some other popular SMTP server programs include Postfix, qmail, Novell GroupWise, Exim, Novell NetMail and Microsoft Exchange Server.
  • Soft32.com Help 11 January 2010 15:19 UTC help.soft32.com [Source type: General]

The SMTP client typically initiates a Transmission Control Protocol (TCP) connection to the SMTP server on the well-known port designated for SMTP, port number 25.
.SMTP is a delivery protocol only.^ Simple Mail Transfer Protocol ( SMTP ): This protocol focuses specifically on how the underlying mail delivery system passes messages from machine to machine.
  • Lesson 26: E-mail, SMTP, and MIME Types 11 January 2010 15:19 UTC www.cis.njit.edu [Source type: Reference]

^ The SMTP protocol requires only that a host be able to send straight ASCII text to another host.
  • The Simple Mail Transfer Protocol is a standard for mail transport 11 January 2010 15:19 UTC www.web-articles.info [Source type: FILTERED WITH BAYES]

^ An extended version of the Simple Mail Transfer Protocol (SMTP), which includes additional functionality, such as delivery notification and session delivery.
  • E-mail Inspection Engine  [Cisco IOS Software Releases 12.3 T] - Cisco Systems 11 January 2010 15:19 UTC cio.cisco.com [Source type: Reference]

.It cannot pull messages from a remote server on demand.^ SMTP is a "push" protocol that cannot "pull" messages from a remote server on demand.
  • CCIE SECApplication Protocols - XMind - Social Brainstorming and Mind Mapping 11 January 2010 15:19 UTC www.xmind.net [Source type: Reference]

^ Messages are stored on a remote server.
  • Cyberoam Knowledge Base 11 January 2010 15:19 UTC kb.cyberoam.com [Source type: Reference]

^ Introduction The SMTP protocol [ 1 ] requires that an SMTP server provide notification of delivery failure, if it determines that a message cannot be delivered to one or more recipients.
  • draft-moore-rfc1891bis-02 - Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs) 11 January 2010 15:19 UTC tools.ietf.org [Source type: Reference]

.Other protocols, such as the Post Office Protocol (POP) and the Internet Message Access Protocol (IMAP) are specifically designed for retrieving messages and managing mail boxes.^ Internet Message Access Protocol ( IMAP ) Industry standard email retrieval and storage protocol.
  • http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/glossary/index.html 11 January 2010 15:19 UTC www.redhat.com [Source type: Reference]

^ EMSD is designed to be a companion to existing Internet mail protocols.
  • Free Protocols Foundation - PLPC-100026: EMSD: The LEAP E-Mail Component 11 January 2010 15:19 UTC www.freeprotocols.org [Source type: Reference]

^ Specifies that the Internet Message Access Protocol (IMAP) is being used.
  • E-mail Inspection Engine  [Cisco IOS Software Releases 12.3 T] - Cisco Systems 11 January 2010 15:19 UTC cio.cisco.com [Source type: Reference]

.However, the SMTP protocol has a feature to initiate mail queue processing on a remote server so that the requesting system may receive any messages destined for it (cf.^ SMTP is a client/server protocol in which an e-mail client connects to the server to transfer e-mail messages.

^ SMTP is the protocol used by mail servers to exchange email messages.
  • EIW Fall 2000 Lecture Notes - Internet Application Protocols 11 January 2010 15:19 UTC www.cs.rpi.edu [Source type: FILTERED WITH BAYES]

^ Simple Mail Transfer Protocol (server) .
  • Microsoft Internet Security & Acceleration Server (ISA) 2000 - Configuring protocol definitions 11 January 2010 15:19 UTC www.microsoft.com [Source type: Reference]

.Remote Message Queue Starting).^ RFC 1985 ] SMTP Service Extension for Remote Message Queue Starting.
  • Protocol: SMTP ( Simple Mail Transfer Protocol ) 11 January 2010 15:19 UTC www.protocolbase.net [Source type: Reference]

.POP and IMAP are preferred protocols when a user's personal computer is only intermittently powered up, or Internet connectivity is only transient and hosts cannot receive message during off-line periods.^ Specifies that the Internet Message Access Protocol (IMAP) is being used.
  • E-mail Inspection Engine  [Cisco IOS Software Releases 12.3 T] - Cisco Systems 11 January 2010 15:19 UTC cio.cisco.com [Source type: Reference]

^ RFC924: Official ARPA-Internet protocols for connecting personal computers to the Internet.

^ Unlike IMAP, POP only retrieves mail from a remote host.
  • E-mail Inspection Engine  [Cisco IOS Software Releases 12.3 T] - Cisco Systems 11 January 2010 15:19 UTC cio.cisco.com [Source type: Reference]

Remote Message Queue Starting

.Remote Message Queue Starting is a feature of the SMTP protocol that permits a remote host to start processing of the mail queue on a server so it may receive messages destined to it by sending the TURN command.^ Exchange SMTP Virtual Server queue records: "The connection was dropped by the remote host."

^ SMTP is a protocol for sending e-mail across the internet.
  • MOREnet - kinetic Resources 11 January 2010 15:19 UTC kinetic.more.net [Source type: Reference]

^ Use server SMTP to send e-mail messages.
  • SMTP downloads on CNET 19 September 2009 6:31 UTC www.cnet.com [Source type: General]

.This feature however was deemed insecure[14] and was extended in RFC 1985 with the ETRN command which operates more securely using an authentication method based on Domain Name System information.^ "Domain Name System Security Extensions," that was published as rfc2065, "Domain Name System Security Extensions" .
  • Internet Draft Database Index - documents related to draft-klyne-hdrreg-mail 11 January 2010 15:19 UTC datatracker.ietf.org [Source type: Reference]

^ Domain Name System label .
  • Search | Novell User Communities 11 January 2010 15:19 UTC www.novell.com [Source type: Reference]

^ DNS See domain name system ( DNS ) .
  • http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/glossary/index.html 11 January 2010 15:19 UTC www.redhat.com [Source type: Reference]

On-Demand Mail Relay

Internationalization

.RFC 5336 describes internationalization features for SMTP, the UTF8SMTP extension, which provides support for multi-byte and non-ASCII characters in email addresses, such as Pelé@live.com (simple diacritic), δοκιμή@παράδειγμα.δοκιμή, and 测试@测试.测试.^ RFC 1651 ] SMTP Service Extensions.
  • Protocol: SMTP ( Simple Mail Transfer Protocol ) 11 January 2010 15:19 UTC www.protocolbase.net [Source type: Reference]

^ "Overview and Framework for Internationalized Email," that was updated by rfc5336, "SMTP Extension for Internationalized Email Addresses" .
  • Internet Draft Database Index - documents related to draft-klyne-hdrreg-mail 11 January 2010 15:19 UTC datatracker.ietf.org [Source type: Reference]

^ The SMTP provider also supports ESMTP ( RFC 1651 ).
  • com.sun.mail.smtp (JavaMail API documentation) 19 September 2009 6:31 UTC java.sun.com [Source type: Reference]

Outgoing mail SMTP server

.An e-mail client requires the name or the IP address of an SMTP server as part of its configuration.^ SMTP is a client/server protocol in which an e-mail client connects to the server to transfer e-mail messages.

^ IP address, name .
  • ftp: the file transfer protocol 11 January 2010 15:19 UTC homepages.udayton.edu [Source type: Reference]

^ The address of the SMTP server to connect to.
  • Class: Net::SMTP 19 September 2009 6:31 UTC www.ruby-doc.org [Source type: Reference]

.The server will deliver messages on behalf of the user.^ SOML FROM: The Send Or MaiL command requires that the mail data be delivered to the user's terminal if the user is active (and accepting terminal messages) on the host.
  • Internet Request for Comments (RFC) 821: Simple Mail Transfer Protocol (Part 1) 11 January 2010 15:19 UTC www.gssnet.com [Source type: Reference]

^ The mail server will then break the recipient address into user (webmaster) and domain ( shortinfosec .net) The mail server needs to know which mail server knows how to deliver an e-mail to webmaster@shortinfosec.net .

^ SENDING AND MAILING The main purpose of SMTP is to deliver messages to user's mailboxes.
  • Internet Request for Comments (RFC) 821: Simple Mail Transfer Protocol (Part 1) 11 January 2010 15:19 UTC www.gssnet.com [Source type: Reference]

.This setting allows for various policies and network designs.^ PAM ) Method that allows a system administrator to set access and authentication policies without having to separately recompile individual programs for such features.
  • http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/glossary/index.html 11 January 2010 15:19 UTC www.redhat.com [Source type: Reference]

^ This example also includes sample output from the show appfw configuration and show ip inspect config commands, which allow you to verify the configured setting for the application policy.
  • E-mail Inspection Engine  [Cisco IOS Software Releases 12.3 T] - Cisco Systems 11 January 2010 15:19 UTC cio.cisco.com [Source type: Reference]

.End users connected to the Internet can use the services of an e-mail provider that is not necessarily the same as their connection provider (ISP).^ Internet Service Provider (ISP) A company that provides access to the Internet.
  • FreeBSD Glossary 11 January 2010 15:19 UTC www.freebsdgr.org [Source type: Reference]

^ An Internet protocol providing e-mail services.
  • E-mail Inspection Engine  [Cisco IOS Software Releases 12.3 T] - Cisco Systems 11 January 2010 15:19 UTC cio.cisco.com [Source type: Reference]

^ An Internet service provider, or ISP, is a company that provides access to the Internet.
  • Email SMTP: Providers and Solutions | Business.com 11 January 2010 15:19 UTC www.business.com [Source type: News]

.Network topology, or the location of a client within a network or outside of a network, is no longer a limiting factor for e-mail submission or delivery.^ If you need to exchange information between modules, no matter within one system or across network, MsgConnect will solve this problem for you.
  • Best free protocol module downloads. HS FTP Client 1.0 C Source Library (File Transfer Protocol - RFC 959) Professional, easy-to-use encryption program for serious users. 11 January 2010 15:19 UTC www.freedownloadmanager.org [Source type: Academic]

^ If the ring is "broken" by one computer losing contact, the network can no longer communicate.
  • Internet Hyper-Glossary 11 January 2010 15:19 UTC www.pagetutor.com [Source type: Reference]

^ EMSD is the basis for the mail submission and delivery protocol to be used when the user’s environment demands efficiency.
  • Free Protocols Foundation - PLPC-100026: EMSD: The LEAP E-Mail Component 11 January 2010 15:19 UTC www.freeprotocols.org [Source type: Reference]

.Modern SMTP servers typically use a client's credentials (authentication) rather than a client's location (IP address), to determine whether it is eligible to relay e-mail.^ Typically, this is done by contacting the SMTP port (port 25) on a mail server.
  • The Simple Mail Transfer Protocol is a standard for mail transport 11 January 2010 15:19 UTC www.web-articles.info [Source type: FILTERED WITH BAYES]

^ The mail is typically removed from the server.
  • InformIT: Security Review of Protocols: The Upper Layers > Messaging 11 January 2010 15:19 UTC www.informit.com [Source type: General]

^ Email address to use for SMTP MAIL command.
  • com.sun.mail.smtp (JavaMail API documentation) 19 September 2009 6:31 UTC java.sun.com [Source type: Reference]

.Server administrators choose whether clients use TCP port 25 (SMTP) or port 587 (Submission), as formalized in RFC 4409, for relaying outbound mail to a mail server.^ Typically, this is done by contacting the SMTP port (port 25) on a mail server.
  • The Simple Mail Transfer Protocol is a standard for mail transport 11 January 2010 15:19 UTC www.web-articles.info [Source type: FILTERED WITH BAYES]

^ Use server SMTP to send e-mail messages.
  • SMTP downloads on CNET 19 September 2009 6:31 UTC www.cnet.com [Source type: General]

^ SMTP is the protocol used by mail servers to exchange email messages.
  • EIW Fall 2000 Lecture Notes - Internet Application Protocols 11 January 2010 15:19 UTC www.cs.rpi.edu [Source type: FILTERED WITH BAYES]

.The specifications and many servers support both.^ In the case of IMAP, the server can be written so as to leave stored mail on the IMAP server, or it can support both "remote" and "local" folders, in this case, "local" meaning on the web server rather than the IMAP server.
  • LAN Mail Protocols Summary (Most recent update: 3/13/99) 11 January 2010 15:19 UTC www.faqs.org [Source type: FILTERED WITH BAYES]

^ In either case, both servers engage in a conversation in which specific newsgroup information is requested and then delivered.
  • Protocol: NNTP ( Network News Transfer Protocol ) 11 January 2010 15:19 UTC www.protocolbase.net [Source type: Academic]

^ Fortunately, many clients can automatically test "what the server supports" to make configuration a little bit easier.
  • Essential Internet Protocols - SMTP 19 September 2009 6:31 UTC www.vanemery.com [Source type: FILTERED WITH BAYES]

.Although some servers support port 465 for legacy secure SMTP in violation of the specifications, it is preferable to use standard ports and standard ESMTP commands[15] according to RFC 3207 if a secure session needs to be used between the client and the server.^ SMTP commands are generated by the SMTP client and sent to the SMTP server .
  • Simple Mail Transfer Protocol [RFC-Ref] 11 January 2010 15:19 UTC rfc-ref.org [Source type: Reference]

^ The port number of the SMTP server to connect to.
  • Class: Net::SMTP 19 September 2009 6:31 UTC www.ruby-doc.org [Source type: Reference]

^ The Simple Mail Transfer Protocol (SMTP) is used to transfer e-mail between servers and clients on the Internet.
  • E-mail Inspection Engine  [Cisco IOS Software Releases 12.3 T] - Cisco Systems 11 January 2010 15:19 UTC cio.cisco.com [Source type: Reference]

.Some servers are set up to reject all relaying on port 25, but valid users authenticating on port 587 are allowed to relay mail to any valid address.^ Typically, this is done by contacting the SMTP port (port 25) on a mail server.
  • The Simple Mail Transfer Protocol is a standard for mail transport 11 January 2010 15:19 UTC www.web-articles.info [Source type: FILTERED WITH BAYES]

^ NONE Allow relayed mail .
  • Frequently Asked Questions 11 January 2010 15:19 UTC www.easy400.net [Source type: FILTERED WITH BAYES]

^ Client access is allowed into the DMZ only if the e-mail server validates the user authentication.
  • E-mail Inspection Engine  [Cisco IOS Software Releases 12.3 T] - Cisco Systems 11 January 2010 15:19 UTC cio.cisco.com [Source type: Reference]

.A server that relays all e-mail for all destinations for all clients connecting to port 25 is known as an open relay and is now generally considered a bad practice worthy of blacklisting.^ The port number of the SMTP server to connect to.
  • Class: Net::SMTP 19 September 2009 6:31 UTC www.ruby-doc.org [Source type: Reference]

^ Typically, this is done by contacting the SMTP port (port 25) on a mail server.
  • The Simple Mail Transfer Protocol is a standard for mail transport 11 January 2010 15:19 UTC www.web-articles.info [Source type: FILTERED WITH BAYES]

^ The client opens a primary connection to a server on the Internet.
  • Microsoft Internet Security & Acceleration Server (ISA) 2000 - Configuring protocol definitions 11 January 2010 15:19 UTC www.microsoft.com [Source type: Reference]

.Some Internet service providers intercept port 25, so that it is not possible for their users to send mail via a relaying SMTP server outside the ISP's network using port 25; they are restricted to using the ISP's SMTP server.^ Typically, this is done by contacting the SMTP port (port 25) on a mail server.
  • The Simple Mail Transfer Protocol is a standard for mail transport 11 January 2010 15:19 UTC www.web-articles.info [Source type: FILTERED WITH BAYES]

^ Internet Service Provider (ISP) A company that provides access to the Internet.
  • FreeBSD Glossary 11 January 2010 15:19 UTC www.freebsdgr.org [Source type: Reference]

^ An Internet protocol providing e-mail services.
  • E-mail Inspection Engine  [Cisco IOS Software Releases 12.3 T] - Cisco Systems 11 January 2010 15:19 UTC cio.cisco.com [Source type: Reference]

.Some independent SMTP servers support an additional port other than 25 to allow users with authenticated access to connect to them even if port 25 is blocked.^ The port number of the SMTP server to connect to.
  • Class: Net::SMTP 19 September 2009 6:31 UTC www.ruby-doc.org [Source type: Reference]

^ The default SMTP port, port 25.
  • Class: Net::SMTP 19 September 2009 6:31 UTC www.ruby-doc.org [Source type: Reference]

^ The address of the SMTP server to connect to.
  • Class: Net::SMTP 19 September 2009 6:31 UTC www.ruby-doc.org [Source type: Reference]

.The practical purpose of this is that a mobile user connecting to different ISPs otherwise has to change SMTP server settings on the mail client for each ISP; using a relaying SMTP server allows the SMTP client settings to be used unchanged worldwide.^ The port number of the SMTP server to connect to.
  • Class: Net::SMTP 19 September 2009 6:31 UTC www.ruby-doc.org [Source type: Reference]

^ Use server SMTP to send e-mail messages.
  • SMTP downloads on CNET 19 September 2009 6:31 UTC www.cnet.com [Source type: General]

^ You can send mail from any mail client that is complaint with SMTP protocol using this server.
  • SMTP Resources | ZDNet 19 September 2009 6:31 UTC updates.zdnet.com [Source type: General]

SMTP transport example

.A typical example of sending a message via SMTP to two mailboxes (alice and theboss) located in the same mail domain (example.com) is reproduced in the following session exchange.^ The MTA that sends an e-mail message.
  • Selected MARID-Related Terms and Acronyms 11 January 2010 15:19 UTC www.technoids.org [Source type: Reference]

^ SMTP is the protocol used by mail servers to exchange email messages.
  • EIW Fall 2000 Lecture Notes - Internet Application Protocols 11 January 2010 15:19 UTC www.cs.rpi.edu [Source type: FILTERED WITH BAYES]

^ SENDING AND MAILING The main purpose of SMTP is to deliver messages to user's mailboxes.
  • Internet Request for Comments (RFC) 821: Simple Mail Transfer Protocol (Part 1) 11 January 2010 15:19 UTC www.gssnet.com [Source type: Reference]

.For illustration purposes here (not part of protocol), the protocol exchanges are prefixed for the server (S:) and the client (C:).^ An email server exchanges emails with other servers using Simple Mail Transfer Protocol (SMTP).
  • Email SMTP: Providers and Solutions | Business.com 11 January 2010 15:19 UTC www.business.com [Source type: News]

^ SMTP is the protocol used by mail servers to exchange email messages.
  • EIW Fall 2000 Lecture Notes - Internet Application Protocols 11 January 2010 15:19 UTC www.cs.rpi.edu [Source type: FILTERED WITH BAYES]

^ The SSL security protocol provides data encryption, server authentication, message integrity, and optional client authentication for a TCP/IP connection.
  • MOREnet - kinetic Resources 11 January 2010 15:19 UTC kinetic.more.net [Source type: Reference]

.After the message sender (SMTP client) establishes a reliable communications channel to the message receiver (SMTP server), the session is opened with a greeting by the server, usually containing its fully qualified domain name, in this case smtp.example.com.^ An MTA-name of type "dns" is a fully-qualified domain name.
  • draft-moore-rfc1891bis-02 - Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs) 11 January 2010 15:19 UTC tools.ietf.org [Source type: Reference]

^ FQDN See fully qualified domain name ( FQDN ) .
  • http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/glossary/index.html 11 January 2010 15:19 UTC www.redhat.com [Source type: Reference]

^ Domain Name System (server) .
  • Microsoft Internet Security & Acceleration Server (ISA) 2000 - Configuring protocol definitions 11 January 2010 15:19 UTC www.microsoft.com [Source type: Reference]

.The client initiates its dialog by responding with a HELO command identifying itself in the command's parameter.^ The client uses an ephemeral port to initiate communications to TFTP server port 69 and the server picks an ephemeral port to respond to the client.
  • Shooting Trouble with IP > Protocols and Packets 11 January 2010 15:19 UTC www.ciscopress.com [Source type: FILTERED WITH BAYES]

^ If more than one of either of these parameters appears in a MAIL command, the ESMTP server SHOULD respond with "501 syntax error in parameters or arguments".
  • draft-moore-rfc1891bis-02 - Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs) 11 January 2010 15:19 UTC tools.ietf.org [Source type: Reference]

^ Once the initial connection is established the client must authenticate itself with the server by supplying a username and password.
  • EIW Fall 2000 Lecture Notes - Internet Application Protocols 11 January 2010 15:19 UTC www.cs.rpi.edu [Source type: FILTERED WITH BAYES]

.
S: 220 smtp.example.com ESMTP Postfix
C: HELO relay.example.org
S: 250 Hello relay.example.org, I am glad to meet you
C: MAIL FROM:<bob@example.org>
S: 250 Ok
C: RCPT TO:<alice@example.com>
S: 250 Ok
C: RCPT TO:<theboss@example.com>
S: 250 Ok
C: DATA
S: 354 End data with <CR><LF>.<CR><LF>
C: From: "Bob Example" <bob@example.org>
C: To: Alice Example <alice@example.com>
C: Cc: theboss@example.com
C: Date: Tue, 15 Jan 2008 16:02:43 -0500
C: Subject: Test message
C:
C: Hello Alice.^ R: 250 OK The mail has now been accepted for Jones and Brown.
  • Internet Request for Comments (RFC) 821: Simple Mail Transfer Protocol (Part 1) 11 January 2010 15:19 UTC www.gssnet.com [Source type: Reference]
  • Protocol: SMTP ( Simple Mail Transfer Protocol ) 11 January 2010 15:19 UTC www.protocolbase.net [Source type: Reference]

^ From time to time, you may need to re-configure your mail when SMTP addresses change.
  • Email SMTP: Providers and Solutions | Business.com 11 January 2010 15:19 UTC www.business.com [Source type: News]

^ And finally, the end of mail data indicator confirms the transaction.
  • Internet Request for Comments (RFC) 821: Simple Mail Transfer Protocol (Part 1) 11 January 2010 15:19 UTC www.gssnet.com [Source type: Reference]

.C: This is a test message with 5 header fields and 4 lines in the message body.^ C: This is a test message with 5 headers and 4 lines in the body.
  • CCIE SECApplication Protocols - XMind - Social Brainstorming and Mind Mapping 11 January 2010 15:19 UTC www.xmind.net [Source type: Reference]

^ Logic bags are used by HTTP in the Unless ( Section 10.40 ) header field as expressions to be tested against the requested resource's header field metainformation.
  • Hypertext Transfer Protocol -- HTTP/1.1 11 January 2010 15:19 UTC www.w3.org [Source type: Reference]

^ However, HTTP/1.1 messages may include a single MIME-Version general-header field to indicate what version of the MIME protocol was used to construct the message.
  • Hypertext Transfer Protocol -- HTTP/1.1 11 January 2010 15:19 UTC www.w3.org [Source type: Reference]

C: Your friend, C: Bob C: . S: 250 Ok: queued as 12345 C: QUIT S: 221 Bye {The server closes the connection}
.The client notifies the receiver of the originating e-mail address of the message in a MAIL FROM command.^ The Internet address from which an e-mail message purports to originate, extracted from e-mail headers.
  • Selected MARID-Related Terms and Acronyms 11 January 2010 15:19 UTC www.technoids.org [Source type: Reference]

^ Client sends a MAIL FROM: command with email address of sender.
  • EIW Fall 2000 Lecture Notes - Internet Application Protocols 11 January 2010 15:19 UTC www.cs.rpi.edu [Source type: FILTERED WITH BAYES]

^ Client sends one or more RCPT TO: commands (one for each receiver) with the email address of the receiver of the mail message.
  • EIW Fall 2000 Lecture Notes - Internet Application Protocols 11 January 2010 15:19 UTC www.cs.rpi.edu [Source type: FILTERED WITH BAYES]

.In this example, the email message is sent to two mailboxes on the same SMTP server: one each for each recipient listed in the To and Cc header fields.^ SMTP is the protocol used by mail servers to exchange email messages.
  • EIW Fall 2000 Lecture Notes - Internet Application Protocols 11 January 2010 15:19 UTC www.cs.rpi.edu [Source type: FILTERED WITH BAYES]

^ One iSeries server and two SMTPs .
  • Frequently Asked Questions 11 January 2010 15:19 UTC www.easy400.net [Source type: FILTERED WITH BAYES]

^ One field in the header is called "Protocol".
  • Karen's Power Tools Newsletter December 16, 2004 11 January 2010 15:19 UTC www.karenware.com [Source type: FILTERED WITH BAYES]

.The corresponding SMTP command is RCPT TO.^ The X-to: field contents are derived from a single RCPT TO: SMTP command.
  • Simple Mail Transfer Protocol 11 January 2010 15:19 UTC www.workers.com.br [Source type: Reference]

^ A conforming SMTP server MUST NOT refuse a RCPT command based on the presence or absence of any of these parameters.
  • draft-moore-rfc1891bis-02 - Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs) 11 January 2010 15:19 UTC tools.ietf.org [Source type: Reference]

^ The local part of the mail address from the RCPT TO: command is mapped into a TSO user ID using the SMTP User Table.
  • Simple Mail Transfer Protocol 11 January 2010 15:19 UTC www.workers.com.br [Source type: Reference]

.Each successful reception and execution of a command is acknowledged by the server with a result code and response message (e.g., 250 Ok).^ This command is successful if the message is delivered to a terminal.
  • Internet Request for Comments (RFC) 821: Simple Mail Transfer Protocol (Part 1) 11 January 2010 15:19 UTC www.gssnet.com [Source type: Reference]

^ Command primitives, result codes and textual responses .
  • An Overview of the File Transfer Protocol 11 January 2010 15:19 UTC www.ncftp.com [Source type: FILTERED WITH BAYES]

^ This command is successful if the message is delivered to the mailbox.
  • Internet Request for Comments (RFC) 821: Simple Mail Transfer Protocol (Part 1) 11 January 2010 15:19 UTC www.gssnet.com [Source type: Reference]

.The transmission of the body of the mail message is initiated with a DATA command after which it is transmitted verbatim line by line and is terminated with a characteristic sequence of a new line (<CR><LF>) with just a single full stop (period) followed by another line indication (<CR><LF>).^ The body of the fax-mail message is sent.
  • Extended Simple Mail Transfer Protocol (ESMTP) Accounting in Store and Forward Fax  [Cisco IOS Software Releases 12.0 T] - Cisco Systems 11 January 2010 15:19 UTC www.cisco.com [Source type: Reference]

^ DATA command, is it possible to have a line in an email message with nothing except a "."?
  • EIW Fall 2000 Lecture Notes - Internet Application Protocols 11 January 2010 15:19 UTC www.cs.rpi.edu [Source type: FILTERED WITH BAYES]

^ CR-LF pair at the end of the last line of text, a period, and another CR-LF pair).
  • Protocol: NNTP ( Network News Transfer Protocol ) 11 January 2010 15:19 UTC www.protocolbase.net [Source type: Academic]

.The QUIT command ends the session.^ The last command in a session must be the QUIT command.
  • Internet Request for Comments (RFC) 821: Simple Mail Transfer Protocol (Part 2) 11 January 2010 15:19 UTC www.gssnet.com [Source type: FILTERED WITH BAYES]

^ The QUIT command can not be used at any other time in a session.
  • Internet Request for Comments (RFC) 821: Simple Mail Transfer Protocol (Part 2) 11 January 2010 15:19 UTC www.gssnet.com [Source type: FILTERED WITH BAYES]

^ At the end of the e-mail session when the client host quits and before the TCP connection is closed, no further client/server interaction is allowed unless the client is reauthenticated.
  • E-mail Inspection Engine  [Cisco IOS Software Releases 12.3 T] - Cisco Systems 11 January 2010 15:19 UTC cio.cisco.com [Source type: Reference]

.If the second recipient were located elsewhere, the client would QUIT and connect to the appropriate SMTP server after the first message had been queued.^ The port number of the SMTP server to connect to.
  • Class: Net::SMTP 19 September 2009 6:31 UTC www.ruby-doc.org [Source type: Reference]

^ SMTP ( server ) ¶ Make a connection to a SMTP server.
  • 7.1. Sending E-mail — Network Programming Study Guide v1.0 11 January 2010 15:19 UTC www.sal.ksu.edu [Source type: Reference]

^ The server process acknowledges the QUIT command and then closes the connection to the client.
  • Protocol: NNTP ( Network News Transfer Protocol ) 11 January 2010 15:19 UTC www.protocolbase.net [Source type: Academic]

.The information that the client sends in the HELO and MAIL FROM commands are added (not seen in example code) as additional header fields to the message by the receiving server.^ For example, an e-mail client is an application that enables you to send and receive e-mail.
  • Protocol: SMTP ( Simple Mail Transfer Protocol ) 11 January 2010 15:19 UTC www.protocolbase.net [Source type: Reference]

^ The MTA that sends an e-mail message.
  • Selected MARID-Related Terms and Acronyms 11 January 2010 15:19 UTC www.technoids.org [Source type: Reference]

^ This is information added to the packet by the sending computer.
  • Understanding Network Protocols 11 January 2010 15:19 UTC www.tech-faq.com [Source type: Reference]

.It adds a Received and Return-Path header field, respectively.^ The returned object may be used as a dictionary to add the mail headers.
  • 7.1. Sending E-mail — Network Programming Study Guide v1.0 11 January 2010 15:19 UTC www.sal.ksu.edu [Source type: Reference]

^ LWS ) field-content = The order in which header fields are received is not significant.
  • Hypertext Transfer Protocol -- HTTP/1.1 11 January 2010 15:19 UTC www.w3.org [Source type: Reference]
  • Hypertext Transfer Protocol -- HTTP/1.0 11 January 2010 15:19 UTC www.w3.org [Source type: Reference]
  • Hypertext Transfer Protocol -- HTTP/1.0 11 January 2010 15:19 UTC ftp.ics.uci.edu [Source type: Reference]

^ Upon receiving of a packet header with the SIZE field set to 0, the total length of the incoming packet must be treated as 2, this packet must be dropped, and the event should be logged.
  • Binkp Specification 11 January 2010 15:19 UTC www.ritlabs.com [Source type: Reference]

Optional extensions

.Although optional and not shown in this example, many clients ask the server for the SMTP extensions that the server supports, by using the EHLO greeting of the extended SMTP specification (RFC 1870).^ RFC 1651 ] SMTP Service Extensions.
  • Protocol: SMTP ( Simple Mail Transfer Protocol ) 11 January 2010 15:19 UTC www.protocolbase.net [Source type: Reference]

^ RFC 1869, SMTP Service Extensions .
  • Extended Simple Mail Transfer Protocol (ESMTP) Accounting in Store and Forward Fax  [Cisco IOS Software Releases 12.0 T] - Cisco Systems 11 January 2010 15:19 UTC www.cisco.com [Source type: Reference]

^ RFC 1425 ] SMTP Service Extensions.
  • Protocol: SMTP ( Simple Mail Transfer Protocol ) 11 January 2010 15:19 UTC www.protocolbase.net [Source type: Reference]

.Clients fall back to HELO only if the server does not respond to EHLO.^ Client access is allowed into the DMZ only if the e-mail server validates the user authentication.
  • E-mail Inspection Engine  [Cisco IOS Software Releases 12.3 T] - Cisco Systems 11 January 2010 15:19 UTC cio.cisco.com [Source type: Reference]

^ If the server responds with code 250 to the EHLO command, and the response includes the EHLO keyword DSN, then the Delivery Status Notification extension (as described in this memo) is supported.
  • draft-moore-rfc1891bis-02 - Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs) 11 January 2010 15:19 UTC tools.ietf.org [Source type: Reference]

^ All DOT-enabled SMTP servers, in addition to the other supported features, reply to the EHLO greeting from the client with a "X-DOT-DATA" response.
  • An Architecture for Internet Data Transfer 11 January 2010 15:19 UTC www.cs.cmu.edu [Source type: Reference]

.Modern clients may use the ESMTP extension keyword SIZE to query the server for the maximum message size that will be accepted.^ The HTTP protocol specifies three possible ways to indicate the end of the data field: 1) if the content length field is present, it indicates the size of the data field; 2) the content type field may specify a delimiter of a MIME multipart message [17] ; and (3) the server (but not the client) may indicate the end of the message simply by closing the TCP connection after the last data byte.
  • Citations: Multipurpose Internet Mail Extensions) Part One: Mechanisms for Specifying and Describing the Format of Internet Message Bodies - Borenstein, Freed (ResearchIndex) 11 January 2010 15:19 UTC citeseer.ist.psu.edu [Source type: Reference]

^ For example, when a client application or browser sends a request to the server using HTTP commands, the server responds with a message containing the protocol version, success or failure code, server information, and body content, depending on the request.
  • Network Protocols | uCertify Articles 11 January 2010 15:19 UTC www.ucertify.com [Source type: Reference]

^ The administrator of the machine revealed that a non-local mailing list to which several users were subscribed had received a message with a maximum-sized email attachment.
  • An Architecture for Internet Data Transfer 11 January 2010 15:19 UTC www.cs.cmu.edu [Source type: Reference]

.Older clients and servers may try to transfer excessively-sized messages that will be rejected after consuming network resources, including connect time to network links that is paid by the minute.^ Central connectivity device for resources on a network.
  • http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/glossary/index.html 11 January 2010 15:19 UTC www.redhat.com [Source type: Reference]

^ A resource for transferring files between a server and a client across an Internet connection.
  • E-commerce | E-mail Orlando 11 January 2010 15:19 UTC www.exadev.com [Source type: Reference]

^ FTP Client: A program that uses FTP to connect to a server and transfer files to and from the server.
  • E-commerce | E-mail Orlando 11 January 2010 15:19 UTC www.exadev.com [Source type: Reference]

.Users can manually determine in advance the maximum size accepted by ESMTP servers.^ The administrator of the machine revealed that a non-local mailing list to which several users were subscribed had received a message with a maximum-sized email attachment.
  • An Architecture for Internet Data Transfer 11 January 2010 15:19 UTC www.cs.cmu.edu [Source type: Reference]

^ Using source routing the receiver-SMTP receives mail to be relayed to another server-SMTP The receiver-SMTP may accept or reject the task of relaying the mail in the same way it accepts or rejects mail for a local user.
  • Internet Request for Comments (RFC) 821: Simple Mail Transfer Protocol (Part 1) 11 January 2010 15:19 UTC www.gssnet.com [Source type: Reference]

^ Implementation limits A conforming MTA MUST accept ESMTP parameters of at least the following sizes: (a) ENVID parameter: 100 characters.
  • draft-moore-rfc1891bis-02 - Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs) 11 January 2010 15:19 UTC tools.ietf.org [Source type: Reference]

.The client replaces the HELO command with the EHLO command.^ On the presentation of X-DOT-DATA by the server, any DOT-enabled client can use the X-DOT-DATA command as a replacement for the "DATA" command.
  • An Architecture for Internet Data Transfer 11 January 2010 15:19 UTC www.cs.cmu.edu [Source type: Reference]

^ The SMTP command EHLO , superseding the earlier HELO, a registry of SMTP service extensions, additional parameters to the SMTP MAIL and RCPT commands, and optional replacements for commands defined in this protocol, such as for DATA in non-ASCII transmissions [ 33 ].
  • Simple Mail Transfer Protocol [RFC-Ref] 11 January 2010 15:19 UTC rfc-ref.org [Source type: Reference]

^ Client establishes TCP connection and sends HELO command with client hostname as parameter.
  • EIW Fall 2000 Lecture Notes - Internet Application Protocols 11 January 2010 15:19 UTC www.cs.rpi.edu [Source type: FILTERED WITH BAYES]

S: 220 smtp2.example.com ESMTP Postfix
C: EHLO bob.example.org
S: 250-smtp2.example.com Hello bob.example.org [192.0.2.201]
S: 250-SIZE 14680064
S: 250-PIPELINING
S: 250 HELP
.Thus smtp2.example.com declares that it will accept a fixed maximum message size no larger than 14,680,064 octets (8-bit bytes).^ The administrator of the machine revealed that a non-local mailing list to which several users were subscribed had received a message with a maximum-sized email attachment.
  • An Architecture for Internet Data Transfer 11 January 2010 15:19 UTC www.cs.cmu.edu [Source type: Reference]

^ Requests for one value, no value specified: First Come First Served; can only be assigned a two-octet value (i.e., a value greater than 255).
  • IANA — Protocol Registries 11 January 2010 15:19 UTC www.iana.org [Source type: Reference]

^ The parameter mxb gives the maximum acceptable size of the Entity-Body, in decimal number of octets, for that range of media types.
  • Hypertext Transfer Protocol -- HTTP/1.1 11 January 2010 15:19 UTC www.w3.org [Source type: Reference]

.Depending on the server's actual resource usage, it may be currently unable to accept a message this large.^ If the user is not active (or not accepting terminal messages) on the host a 450 reply may returned to a RCPT command.
  • Internet Request for Comments (RFC) 821: Simple Mail Transfer Protocol (Part 1) 11 January 2010 15:19 UTC www.gssnet.com [Source type: Reference]

^ The actual method for determining how the resource is placed, and what happens to its predecessor, is defined entirely by the origin server.
  • Hypertext Transfer Protocol -- HTTP/1.1 11 January 2010 15:19 UTC www.w3.org [Source type: Reference]
  • Hypertext Transfer Protocol -- HTTP/1.0 11 January 2010 15:19 UTC ftp.ics.uci.edu [Source type: Reference]

^ Similarly, pragma directives are not applicable to the origin of a resource, though they may be applicable to a server's internal response cache.
  • Hypertext Transfer Protocol -- HTTP/1.0 11 January 2010 15:19 UTC ftp.ics.uci.edu [Source type: Reference]

.In the simplest case, an ESMTP server will declare a maximum SIZE with only the EHLO user interaction.^ The administrator of the machine revealed that a non-local mailing list to which several users were subscribed had received a message with a maximum-sized email attachment.
  • An Architecture for Internet Data Transfer 11 January 2010 15:19 UTC www.cs.cmu.edu [Source type: Reference]

^ Only the message header and sender information are displayed in the Inbox until the user downloads the entire message, including attachments, from the server.
  • E-mail Inspection Engine  [Cisco IOS Software Releases 12.3 T] - Cisco Systems 11 January 2010 15:19 UTC cio.cisco.com [Source type: Reference]

^ No meaning is assigned by the mail system to the presence or absence of this parameter or to any esmtp-value associated with this parameter; the information is used only by the sender or his user agent.
  • draft-moore-rfc1891bis-02 - Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs) 11 January 2010 15:19 UTC tools.ietf.org [Source type: Reference]

Security and spamming

.The original SMTP specification did not include a facility for authentication of senders.^ One of the limitations of the original SMTP is that it has no facility for authentication of senders.
  • CCIE SECApplication Protocols - XMind - Social Brainstorming and Mind Mapping 11 January 2010 15:19 UTC www.xmind.net [Source type: Reference]

^ The realm value is a string, generally assigned by the origin server, which may have additional semantics specific to the authentication scheme.
  • Hypertext Transfer Protocol -- HTTP/1.0 11 January 2010 15:19 UTC www.w3.org [Source type: Reference]

^ SMTP transaction, an envelope identification string, which may be used by the sender to associate any delivery status notifications with the transaction used to send the original message.
  • draft-moore-rfc1891bis-02 - Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs) 11 January 2010 15:19 UTC tools.ietf.org [Source type: Reference]

.Subsequently, the SMTP-AUTH extension was defined by RFC 2554.^ RFC 1869, SMTP Service Extensions .
  • Extended Simple Mail Transfer Protocol (ESMTP) Accounting in Store and Forward Fax  [Cisco IOS Software Releases 12.0 T] - Cisco Systems 11 January 2010 15:19 UTC www.cisco.com [Source type: Reference]

^ RFC 1651 ] SMTP Service Extensions.
  • Protocol: SMTP ( Simple Mail Transfer Protocol ) 11 January 2010 15:19 UTC www.protocolbase.net [Source type: Reference]

^ RFC 1425 ] SMTP Service Extensions.
  • Protocol: SMTP ( Simple Mail Transfer Protocol ) 11 January 2010 15:19 UTC www.protocolbase.net [Source type: Reference]

[16] .The SMTP extension (ESMTP) provides a mechanism for email clients to specify a security mechanism to a mail server, authenticate the exchange, and negotiate a security profile (Simple Authentication and Security Layer, SASL) for subsequent message transfers.^ An email server exchanges emails with other servers using Simple Mail Transfer Protocol (SMTP).
  • Email SMTP: Providers and Solutions | Business.com 11 January 2010 15:19 UTC www.business.com [Source type: News]

^ Simple Mail Transfer Protocol (server) .
  • Microsoft Internet Security & Acceleration Server (ISA) 2000 - Configuring protocol definitions 11 January 2010 15:19 UTC www.microsoft.com [Source type: Reference]

^ The Simple Mail Transfer Protocol (SMTP) is used to transfer e-mail between servers and clients on the Internet.
  • E-mail Inspection Engine  [Cisco IOS Software Releases 12.3 T] - Cisco Systems 11 January 2010 15:19 UTC cio.cisco.com [Source type: Reference]

.Microsoft products implement the proprietary Secure Password Authentication (SPA) protocol through the use of the SMTP-AUTH extension.^ TLS ) A secure transmission protocol using data encryption and authentication.
  • http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/glossary/index.html 11 January 2010 15:19 UTC www.redhat.com [Source type: Reference]

^ Therefore the SMTP-AUTH extension was defined.
  • CCIE SECApplication Protocols - XMind - Social Brainstorming and Mind Mapping 11 January 2010 15:19 UTC www.xmind.net [Source type: Reference]

^ However, the impracticalities of widespread SMTP-AUTH implementation and management means that E-mail spamming is not and cannot be addressed by it.
  • CCIE SECApplication Protocols - XMind - Social Brainstorming and Mind Mapping 11 January 2010 15:19 UTC www.xmind.net [Source type: Reference]

.However, the impracticality of widespread SMTP-AUTH implementation and management means that E-mail spamming is not and cannot be addressed by it.^ However, the impracticalities of widespread SMTP-AUTH implementation and management means that E-mail spamming is not and cannot be addressed by it.
  • CCIE SECApplication Protocols - XMind - Social Brainstorming and Mind Mapping 11 January 2010 15:19 UTC www.xmind.net [Source type: Reference]

^ Most commercial e-mail server software includes features to stop junk e-mail, as do popular open source SMTP server implementations, including Sendmail, Postfix, and QMail.

^ If you receive mail through a mail-management software program, the program must be configured to retrieve mail using the SMTP address of the mail server site and the POP or IMAP address of your email client.
  • Email SMTP: Providers and Solutions | Business.com 11 January 2010 15:19 UTC www.business.com [Source type: News]

.Modifying SMTP extensively, or replacing it completely, is not believed to be practical, due to the network effects of the huge installed base of SMTP. Internet Mail 2000 was one such proposal for replacement.^ SMTP Simple Mail Transfer Protocol The standard e-mail protocol on the Internet and part of the TCP/IP protocol suite, as defined by IETF RFC 2821.
  • SMTP Resources | ZDNet 19 September 2009 6:31 UTC updates.zdnet.com [Source type: General]

^ A network that was established to provide mail forwarding and Internet connectivity to computer (and now other) science researchers.
  • DEFINITIONS AND TERMS 11 January 2010 15:19 UTC www.columbia.edu [Source type: Reference]

^ Email (Electronic Mail): An Internet service that allows you to send and receive messages from one computer to another.
  • E-commerce | E-mail Orlando 11 January 2010 15:19 UTC www.exadev.com [Source type: Reference]

.Spam is enabled by several factors, including vendors implementing broken MTAs (that do not adhere to standards, and therefore make it difficult for other MTAs to enforce standards), security vulnerabilities within the operating system (often exacerbated by always-on broadband connections) that allow spammers to remotely control end-user PCs and cause them to send spam, and a lack of "intelligence" in many MTAs.^ FTP is available on several operating systems.
  • DEFINITIONS AND TERMS 11 January 2010 15:19 UTC www.columbia.edu [Source type: Reference]

^ Many other options are supported including return-receipt processing, stdin filtering, console window hiding, custom SMTP headers, non-standard SMTP port usage, HTML files, and pager support.
  • SMTP downloads at VicMan 19 September 2009 6:31 UTC vicman.net [Source type: General]

^ Today Sendmail is included in the base system, but there are many other MTA s, such as postfix, qmail and Exim.
  • FreeBSD Glossary 11 January 2010 15:19 UTC www.freebsdgr.org [Source type: Reference]

.There are a number of proposals for sideband protocols that will assist SMTP operation.^ Page 4 Protocol Numbers PROTOCOL NUMBERS In the Internet Protocol (IP) [36,80] there is a field, called Protocol, to identify the the next level protocol.

^ This proposed protocol is designed to operate over a full duplex point-to-point connection.
  • Official ARPA-Internet protocols - The H Security: News and features 11 January 2010 15:19 UTC www.h-online.com [Source type: Reference]

^ There are many different aspects of Simple Mail Transfer Protocol you'll need to know when working with email SMTP providers.
  • Email SMTP: Providers and Solutions | Business.com 11 January 2010 15:19 UTC www.business.com [Source type: News]

.The Anti-Spam Research Group (ASRG) of the Internet Research Task Force (IRTF) is working on a number of E-mail authentication and other proposals for providing simple source authentication that is flexible, lightweight, and scalable.^ We provide this service in coordination with the Internet Engineering Task Force (IETF).
  • IANA — Protocol Registries 11 January 2010 15:19 UTC www.iana.org [Source type: Reference]

^ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups.
  • draft-moore-rfc1891bis-02 - Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs) 11 January 2010 15:19 UTC tools.ietf.org [Source type: Reference]
  • Hypertext Transfer Protocol -- HTTP/1.1 11 January 2010 15:19 UTC www.w3.org [Source type: Reference]
  • Hypertext Transfer Protocol -- HTTP/1.0 11 January 2010 15:19 UTC www.w3.org [Source type: Reference]
  • Hypertext Transfer Protocol -- HTTP/1.0 11 January 2010 15:19 UTC ftp.ics.uci.edu [Source type: Reference]

^ RFC ) A technical note submitted to the Internet Engineering Task Force ( IETF ) that describes novel techniques or technologies that can be eventually voted into a standard.
  • http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/glossary/index.html 11 January 2010 15:19 UTC www.redhat.com [Source type: Reference]

Recent Internet Engineering Task Force (IETF) activities include MARID (2004) leading to two approved IETF experiments in 2005, and DomainKeys Identified Mail in 2006.

Implementations

Related Requests For Comments

  • RFC 1123 – Requirements for Internet Hosts—Application and Support (STD 3)
  • RFC 1870 – SMTP Service Extension for Message Size Declaration (оbsoletes: RFC 1653)
  • RFC 2505 – Anti-Spam Recommendations for SMTP MTAs (BCP 30)
  • RFC 2920 – SMTP Service Extension for Command Pipelining (STD 60)
  • RFC 3030 – SMTP Service Extensions for Transmission of Large and Binary MIME Messages
  • RFC 3207 – SMTP Service Extension for Secure SMTP over Transport Layer Security (obsoletes RFC 2487)
  • RFC 3461 – SMTP Service Extension for Delivery Status Notifications (obsoletes RFC 1891)
  • RFC 3462 – The Multipart/Report Content Type for the Reporting of Mail System Administrative Messages (obsoletes RFC 1892)
  • RFC 3463 – Enhanced Status Codes for SMTP (obsoletes RFC 1893 )
  • RFC 3464 – An Extensible Message Format for Delivery Status Notifications (obsoletes RFC 1894)
  • RFC 3834 – Recommendations for Automatic Responses to Electronic Mail
  • RFC 4409 – Message Submission for Mail (obsoletes RFC 2476)
  • RFC 4952 – Overview and Framework for Internationalized E-mail
  • RFC 4954 – SMTP Service Extension for Authentication (obsoletes RFC 2554)
  • RFC 5068 – E-mail Submission Operations: Access and Accountability Requirements (BCP 134)
  • RFC 5321 – The Simple Mail Transfer Protocol (obsoletes RFC 821 aka STD 10, RFC 974, RFC 1869, RFC 2821)
  • RFC 5322 – Internet Message Format (obsoletes RFC 822 aka STD 11, and RFC 2822)
  • RFC 5336 - SMTP Extension for Internationalized Email Addresses (updates RFC 2821, RFC 2822, and RFC 4952)
  • RFC 5504 - Downgrading Mechanism for Email Address Internationalization

See also

References

  1. ^ RFC 821, Simple Mail Transfer Protocol, J.B. Postel, The Internet Society (August 1982)
  2. ^ a b c RFC 5321, Simple Mail Transfer Protocol, J. Klensin, The Internet Society (October 2008)
  3. ^ The History of Electronic Mail, Tom Van Vleck: "It is not clear this protocol was ever implemented"
  4. ^ The First Network Email, Ray Tomlinson, BBN
  5. ^ Picture of "The First Email Computer" by Dan Murphy, a PDP-10
  6. ^ Dan Murphy's TENEX and TOPS-20 Papers
  7. ^ RFC 2235
  8. ^ RFC 469 - Network Mail Meeting Summary
  9. ^ RFC 524 - A Proposed Mail Protocol
  10. ^ RFC 772 - Mail Transfer Protocol
  11. ^ Tldp.org
  12. ^ draft-barber-uucp-project-conclusion-05 - The Conclusion of the UUCP Mapping Project
  13. ^ RFC 4409, Message Submission for Mail, R. Gellens, J. Klensin, The Internet Society (April 2006)
  14. ^ RFC 1985, SMTP Service Extension for Remote Message Queue Starting, J. De Winter, The Internet Society (August 1996)
  15. ^ RFC 3207 specifies only the well-known port 25 and the "Submission port," which is TCP port 587, for the STARTTLS command, the precursor for an encrypted SMTP session using TLS. It makes no mention of the unofficial port 465.
  16. ^ RFC 2554, SMTP Service Extension for Authentication, J. Myers (March 1999)

Further reading

  • Hughes, L (1998). .Internet e-mail Protocols, Standards and Implementation.^ An Internet protocol providing e-mail services.
    • E-mail Inspection Engine  [Cisco IOS Software Releases 12.3 T] - Cisco Systems 11 January 2010 15:19 UTC cio.cisco.com [Source type: Reference]

    ^ RFC760: DoD standard Internet Protocol.

    ^ This standard protocol is built into most popular e-mail products, such as Eudora and Outlook Express.
    • Protocol: SMTP ( Simple Mail Transfer Protocol ) 11 January 2010 15:19 UTC www.protocolbase.net [Source type: Reference]
    • Protocol: NNTP ( Network News Transfer Protocol ) 11 January 2010 15:19 UTC www.protocolbase.net [Source type: Academic]

    Artech House Publishers. ISBN 0890069395.
     
  • Hunt, C (2003). sendmail Cookbook. O'Reilly Media. ISBN 0596004710. 
  • Johnson, K (2000). .Internet Email Protocols: A Developer's Guide.^ Internet Message Access Protocol ( IMAP ) Industry standard email retrieval and storage protocol.
    • http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/glossary/index.html 11 January 2010 15:19 UTC www.redhat.com [Source type: Reference]

    ^ SNMP Simple Network Management Protocol, developed by the Internet community to allow diverse network objects to participate in a global network management architecture.
    • Protocols - Acronyms List 11 January 2010 15:19 UTC www.protocols.com [Source type: Reference]

    ^ Simple Network Management Protocol (SNMP) Developed to manage nodes on an IP network, SNMP is an Internet standard protocol .
    • Internet Hyper-Glossary 11 January 2010 15:19 UTC www.pagetutor.com [Source type: Reference]

    Addison-Wesley Professional. ISBN 0201432889.
     
  • Loshin, P (1999). .Essential Email Standards: RFCs and Protocols Made Practical.^ Internet Official Protocol Standards (Obsoleted by RFC-2800 -> RFC-2900 -> RFC-3000 -> RFC-3300 -> RFC-3600 -> RFC-3700 std1 ) .
    • SIMPLE MAIL TRANSFER PROTOCOL [RFC-Ref] 11 January 2010 15:19 UTC rfc-ref.org [Source type: Reference]

    ^ Internet Message Access Protocol ( IMAP ) Industry standard email retrieval and storage protocol.
    • http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/glossary/index.html 11 January 2010 15:19 UTC www.redhat.com [Source type: Reference]

    ^ The Internet and the DoD MIL-STD specifications for the FTP, SMTP, and Telnet protocols are essentially the same documents (RFCs 765, 821, 854).
    • rfc1500 - INTERNET OFFICIAL PROTOCOL STANDARDS 11 January 2010 15:19 UTC aurora.rg.iupui.edu [Source type: Reference]

    John Wiley & Sons. ISBN 0471345970.
     
  • Rhoton, J (1999). .Programmer's Guide to Internet Mail: SMTP, POP, IMAP, and LDAP.^ The SMTP protocol is to be used for all mail service in the Internet.
    • RFC 901 - Official ARPA-Internet protocols 11 January 2010 15:19 UTC www.packetizer.com [Source type: Reference]

    ^ IMAP (Internet Message Access Protocol) is an Internet standard for the reading and manipulation of e-mail messages stored on a server.
    • Cyberoam Knowledge Base 11 January 2010 15:19 UTC kb.cyberoam.com [Source type: Reference]

    ^ Kernel Security International SMTP (Simple Mail Transfer Protocol) IMAP (Internet Message Access Protocol) POP and RPOP (Post Office Protocol) HTTP (HyperText Transfer Protocol) FTP (File Transfer Protocol) LDAP (Lightweight Directory Access Protocol) Mailing Lists ACAP (Application Configuration Access Protocol) DNR (Domain Name Resolver) SNMP (Simple Network Management Protocol) Web User Interface .

    Elsevier. ISBN 1555582125.
     
  • Wood, D (1999). .Programming Internet Mail.^ Individual users communicate by using application programs, such as electronic mail, TELNET, and FTP.  ICMP Internet Control Message Protocol.
    • DEFINITIONS AND TERMS 11 January 2010 15:19 UTC www.columbia.edu [Source type: Reference]

    ^ A program that provides Internet File Transfer Protocol (FTP) access to local files is usually called an FTP server.  SMTP Simple Mail Transfer Protocol.
    • DEFINITIONS AND TERMS 11 January 2010 15:19 UTC www.columbia.edu [Source type: Reference]

    O'Reilly. ISBN 1565924797.
     

External links


Citable sentences

Up to date as of December 23, 2010

Here are sentences from other pages on Simple Mail Transfer Protocol, which are similar to those in the above article.








Got something to say? Make a comment.
Your name
Your email address
Message