Postfix is a free software / open source mail transfer agent (MTA), a computer program for the routing and delivery of email. It is intended as a fast, easy-to-administer, and secure alternative to the widely-used Sendmail MTA. Image File history File links No higher resolution available. ... Software development is the translation of a user need or marketing goal into a software product. ... Wietse Venema speaking at a conference in 2004 Dr. Wietse Zweitze Venema (born 1951) is a Dutch programmer and physicist best known for writing the Postfix mail system. ... A software release is the distribution, whether public or private, of an initial or new and upgraded version of a computer software product. ... is the 151st day of the year (152nd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st Century. ... A software release is the distribution, whether public or private, of an initial or new and upgraded version of a computer software product. ... is the 151st day of the year (152nd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st Century. ... // An operating system (OS) is the software that manages the sharing of the resources of a computer. ... A cross-platform (or platform independent) programming language, software application or hardware device works on more than one system platform (e. ... Computer software can be organized into categories based on common function, type, or field of use. ... A mail transfer agent or MTA (also called a mail transport agent, mail server, or a mail exchanger in the context of the Domain Name System) is a computer program or software agent that transfers electronic mail messages from one computer to another. ... A software license is a legal agreement which may take the form of a proprietary or gratuitous license as well as a memorandum of contract between a producer and a user of computer software. ... The IBM Public License is a free software / open-source software license used by IBM. It is ratified by the Open Source Initiative and Free Software Foundation (FSF). ... A website (alternatively, Web site or web site) is a collection of Web pages, images, videos and other digital assets that is hosted on one or several Web server(s), usually accessible via the Internet, cell phone or a LAN. A Web page is a document, typically written in HTML... This article is about free software as used in the sociopolitical free software movement; for non-free software distributed without charge, see freeware. ... Open source software is computer software which source code is available under a license (or arrangement such as the public domain) that meets the Open_source_definition. ... A mail transfer agent or MTA (also called a mail transport agent, mail server, or a mail exchanger in the context of the Domain Name System) is a computer program or software agent that transfers electronic mail messages from one computer to another. ... A computer program is a collection of instructions that describe a task, or set of tasks, to be carried out by a computer. ... E-mail, or email, is short for electronic mail and is a method of composing, sending, and receiving messages over electronic communication systems. ... Sendmail is a mail transfer agent (MTA) that is a well known project of the open source, free software and Unix communities, which is distributed both as free software and proprietary software. ...

Postfix is the default MTA for a number of Unix(-like) operating systems. Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... Diagram of the relationships between several Unix-like systems A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification. ...

It is released under the IBM Public License 1.0 which is a free software licence, but is incompatible with the GPL. The IBM Public License is a free software / open-source software license used by IBM. It is ratified by the Open Source Initiative and Free Software Foundation (FSF). ... A free software licence is a software licence which grants recipients rights to modify and redistribute the software which would otherwise be prohibited by copyright law. ... The GNU logo The GNU General Public License (GNU GPL or simply GPL) is a widely-used free software license, originally written by Richard Stallman for the GNU project. ...

Postfix's source code is often used as a famous example of good programming practice.

Formerly known as VMailer and IBM Secure Mailer, it was originally written by Wietse Venema during a stay at the IBM Thomas J. Watson Research Center, and continues to be actively developed today. Postfix was first released in mid-1999. Wietse Venema speaking at a conference in 2004 Dr. Wietse Zweitze Venema (born 1951) is a Dutch programmer and physicist best known for writing the Postfix mail system. ... For other uses, see IBM (disambiguation) and Big Blue. ... The Thomas J. Watson Research Center is the headquarters for the IBM Research Division. ... This article is about the year. ...

Features

• Transport Layer Security (TLS)
• delegation of SMTP policies to an external process (this allows Greylisting) and advanced content filtering.
• different databases for maps: Berkeley DB, CDB, DBM, LDAP, MySQL and PostgreSQL.
• mbox-style mailboxes, Maildir-style mailboxes, and virtual domains.
• address rewriting (envelope and header), VERP, SMTP-AUTH via SASL, and much more.
• Milter [1] support
• can be compiled on AIX, BSD, HP-UX, IRIX, Linux, Mac OS X, Solaris, Tru64 UNIX and, generally speaking, on every Unix-like OS that ships with a C compiler, standard POSIX development libraries and all the libraries required for handling BSD sockets.

One of the strengths of Postfix is its resilience against buffer overflows. Another one is its handling of large amounts of e-mail. Postfix is built as a cooperating network of different daemons. Each daemon fulfills a single task using minimum privileges. In this way, if a daemon is compromised, the impact remains limited to that daemon and cannot spread throughout the entire system. There is only one process with root privileges (master), and a few (local, virtual, pipe) that actually write to disk or invoke external programs. Most daemons can be easily chrooted. Transport Layer Security (TLS) and its predecessor, Secure Sockets Layer (SSL), are cryptographic protocols that provide secure communications on the Internet for such things as web browsing, e-mail, Internet faxing, instant messaging and other data transfers. ... Simple Mail Transfer Protocol (SMTP) is the de facto standard for e-mail transmissions across the Internet. ... Greylisting (sometimes spelled graylisting in the United States) is a method of defending electronic mail users against e-mail spam. ... This article is about computing. ... Berkeley DB (BDB) is a high-performance, embedded database library with bindings in C, C++, Java, Perl, Python, Ruby, Tcl, Smalltalk and many other programming languages. ... An editor has expressed a concern that the subject of the article does not satisfy the notability guideline or one of the following guidelines for inclusion on Wikipedia: Biographies, Books, Companies, Fiction, Music, Neologisms, Numbers, Web content, or several proposals for new guidelines. ... The Lightweight Directory Access Protocol, or LDAP (IPA: ), is an application protocol for querying and modifying directory services running over TCP/IP.[1] A directory is a set of information with similar attributes organized in a logical and hierarchical manner. ... MySQL (pronounced (IPA) , my S-Q-L) is a multithreaded, multi-user SQL database management system (DBMS)[1] which has, according to MySQL AB, more than 10 million installations. ... PostgreSQL is a free software object-relational database management system (ORDBMS), released under a BSD-style license. ... Mbox is the name for several different things, including an electronic mail file format. ... Maildir is a format for an e-mail spool that does not require file locking to maintain message integrity because the messages are kept in separate files with unique names. ... In information technology, Header refers to supplemental data placed at the beginning of a block of data being stored or transmitted, which contain information for the handling of the data block. ... Variable envelope return path (VERP) is a technique used by some electronic mailing list software to enable automatic detection and removal of undeliverable e-mail addresses. ... SMTP-AUTH extends SMTP (the Internet e-mail transmission protocol) to include an authentication step through which the client effectively logs in to the mail server during the process of sending mail. ... Simple Authentication and Security Layer (SASL) is a framework for authentication and authorization in Internet protocols. ... A milter is an extension to the widely used open source mail transfer agent (MTA) sendmail. ... AIX (Advanced Interactive eXecutive) is a proprietary operating system developed by IBM based on UNIX System V. Before the product was ever marketed, the acronym AIX originally stood for Advanced IBM UNIX. AIX has pioneered numerous network operating system enhancements, introducing new innovations later adopted by Unix-like operating systems... BSD redirects here; for other uses see BSD (disambiguation). ... HP-UX (Hewlett Packard UniX) is Hewlett-Packards proprietary implementation of the Unix operating system, based on System V (initially System III). ... IRIX is a computer operating system developed by Silicon Graphics, Inc. ... This article is about operating systems that use the Linux kernel. ... Mac OS X (IPA: ) is a line of graphical operating systems developed, marketed, and sold by Apple Inc. ... Solaris is a computer operating system developed by Sun Microsystems. ... Tru64 is HPs (formerly Compaq; formerly DEC) 64-bit UNIX for the Alpha AXP platform. ... C is a general-purpose, block structured, procedural, imperative computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system. ... A diagram of the operation of a typical multi-language, multi-target compiler. ... POSIX or Portable Operating System Interface[1] is the collective name of a family of related standards specified by the IEEE to define the application programming interface (API) for software compatible with variants of the Unix operating system. ... Illustration of an application which may use libvorbisfile. ... The Berkeley sockets application programming interface (API) comprises a library for developing applications in the C programming language that perform inter-process communication, most commonly across a computer network. ... In computer security and programming, a buffer overflow, or buffer overrun, is a programming error which may result in a memory access exception and program termination, or in the event of the user being malicious, a possible breach of system security. ... In Unix and other computer multitasking operating systems, a daemon is a computer program that runs in the background, rather than under the direct control of a user; they are usually instantiated as processes. ... A privilege in a computer system is a permission to perform an action. ... A chroot on Unix operating systems is an operation which changes the root directory. ...

Structure

See Postfix Architecture Overview

Base configuration

The main.cf file stores site specific Postfix configuration parameters while master.cf defines daemon processes. The Postfix Basic Configuration tutorial covers the core settings that each site needs to consider.

Configuration settings for a few common environments are discussed in Postfix Standard Configuration Examples.

Address rewriting and mail routing are covered in Postfix Address Rewriting. The full documentation collection is at Postfix Documentation

References

• Kyle D. Dent (2003). Postfix: The Definitive Guide. O'Reilly Media. ISBN 0-596-00212-2. 
• Ralf Hildebrandt and Patrick Koetter (2005). The book of Postfix : state-of-the-art message transport. No Starch Press. ISBN 1-59327-001-1. 

Programming Perl is a classic OReilly book. ... No Starch Press is a publishing company specializing in computer books for the technically savvy, or geek entertainment as they term it. ...

See also

• List of mail servers
• Comparison of mail servers

Image File history File links Free_Software_Portal_Logo. ... This is a list of mail servers: mail transfer agents, mail delivery agents, and other computer software which provide e-mail services. ... It has been suggested that this article or section be merged with List of mail servers. ...

External links

• Official website
• Postfix Discussion (mailing list archive)
• http://www.postfixwiki.org/
• http://serverkit.org/modules/postfix-policy A high performance Postfix policy delegation server
• http://www.360is.com/06-postfix.htm Postfix introduction and analysis for secure environments