Postfix feature overview

Supported environments

Postfix runs on AIX, BSD, HP-UX, IRIX, LINUX, MacOS X, Solaris, Tru64 UNIX, and other UNIX systems. It requires ANSI C, a POSIX.1 library, and BSD sockets. See below for the gory details of what Postfix expects from the file system.

Gory details: the Postfix mail queue requires that (1) the file system can rename a file to a near-by directory without changing the file's inode number, and that (2) mail is safely stored after fsync() of that file (not its parent directory) returns successfully, even when that file is renamed to a near-by directory at some later point in time. Maildir delivery also requires that (3) a file can be hard linked between different near-by directories. Mailbox delivery introduces no additional requirements beyond what is already needed for Postfix queues.

Main features

The following is a list of major Postfix features. Some features require third-party libraries (examples: LDAP, SQL, TLS). Other features are available only when the necessary operating system support exists and Postfix knows how to use it (examples: IP version 6, connection caching).

Protocol support

Postfix 2.2	Connection cache for SMTP
Postfix 2.3	DKIM, DomainKeys and SenderID authentication (via Milter plug-in)
Postfix 2.3	DSN status notifications
Postfix 2.3	Enhanced status codes
Postfix 1.0	ETRN on-demand relay
Postfix 2.2	IP version 6
Postfix 1.0	LMTP client
Postfix 2.0	MIME (including 8BITMIME to 7BIT conversion)
Postfix 1.0	Pipelining (SMTP client and server)
Postfix 2.3	Plug-in support for multiple SASL implementations (Cyrus, Dovecot)
Postfix 1.0	SASL authentication
Postfix 2.2	TLS encryption and authentication
Postfix 1.1	QMQP server

By popular demand...

Postfix 2.3	Configurable delivery status notification message text
Postfix 2.3	Sender-dependent SMTP relay lookup
Postfix 2.3	Sender-dependent SASL password lookup
Postfix 2.8	Server reject "footer" text

Junk mail control

Postfix 2.8	Zombie blocker (postscreen).
Postfix 2.8	DNS whitelist support in smtpd and in postscreen.
Postfix 2.1	Access control per client/sender/recipient/etc.
Postfix 2.1	Address probing callout
Postfix 1.1	Content filter (built-in, external before queue, external after queue)
Postfix 2.3	Sendmail Milter (mail filter) protocol
Postfix 2.1	Greylisting plug-in
Postfix 2.1	SPF plug-in
Postfix 2.2	SMTP server per-client rate and concurrency limits
Postfix 2.5	Stress-dependent configuration

Database support

Postfix 1.0	Berkeley DB database
Postfix 2.2	CDB database
Postfix 1.0	DBM database
Postfix 1.0	LDAP database
Postfix 1.0	MySQL database
Postfix 2.0	PostgreSQL database
Postfix 2.8	SQLite database

Mailbox support

Postfix 1.0	Maildir and mailbox format
Postfix 1.0	Virtual domains

Address manipulation

Postfix 2.2	Masquerading addresses in outbound SMTP mail
Postfix 2.2	Selective address rewriting
Postfix 1.1	VERP envelope return addresses