View source for Software:Mail delivery agent

A '''mail delivery agent''' or '''message delivery agent''' ('''MDA''') is a computer [[Software|software]] component that is responsible for the delivery of e-mail messages to a local recipient's mailbox.<ref>{{IETF RFC|5598}}, ''Internet Mail Architecture'', D. Crocker (July 2009)</ref> It is also called a '''local delivery agent''' ('''LDA''').
Within the Internet mail architecture, local message delivery is achieved through a process of handling messages from the message transfer agent, and storing mail into the recipient's environment (typically a mailbox).

==Implementation==

Many mail handling software products bundle multiple message delivery agents with the [[Message transfer agent|message transfer agent]] component, providing for site customization of the specifics of mail delivery to a user.

=== Unix ===

On [[Unix-like]] systems, [[Software:Procmail|procmail]] and [[Software:Maildrop|maildrop]] are the most popular MDAs.  The [[Local Mail Transfer Protocol]] (LMTP) is a protocol that is frequently implemented by network-aware MDAs.{{Citation needed|date=February 2010}}

==== Invocation ====

The mail delivery agent is generally not started from the command line, but is usually invoked by mail delivery subsystems, such as a mail transport agent, or a mail retrieval agent.

==== List of MDA software for Unix-like platforms ====
* Cyrus IMAP - A mail server suite that includes a mail delivery agent
* [[Software:Dovecot|dovecot]] - A mail server suite that includes a mail delivery agent
* [[Software:Fetchmail|fetchmail]] - Primarily a Mail retrieval agent (MRA)
* [[Software:Getmail|getmail]] - simpler, more secure, modern [[Software:Fetchmail|fetchmail]] alternative
* [[Software:Fdm|fdm]] — modern replacement for both [[Software:Fetchmail|fetchmail]] and [[Software:Procmail|procmail]] from the author of [[Software:Tmux|tmux]]
* [[Software:Maildrop|maildrop]] or courier-maildrop - traditional procmail replacement, part of [[Software:Courier Mail Server|Courier Mail Server]], but can also be used with other mail servers
* [[Software:Procmail|procmail]] - obsolete since it is unmaintained; old, but still used
* bin/mail, the MDA part of [[Software:Sendmail|Sendmail]] - Sendmail is one of the oldest email packages
* [[Software:Sieve (mail filtering language)|Sieve mail filtering language]] - a standardised mail filtering language; also, a modern replacement for procmail from the GNU Mailutils package

==See also==
* [[Message transfer agent]] (MTA)
* Mail retrieval agent (MRA)
* Mail submission agent (MSA)
* Mail user agent (MUA) a.k.a. email client
* E-mail agent (infrastructure) (MxA)

==References==
{{reflist}}

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