= Postfix Local Delivery =

There are a number of additional considerations when delivering mail locally through Postfix.

<<TableOfContents>>

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== Mail Manipulations ==

Mail is delivered to a user-specific folder under `mail_spool_directory`, i.e. `/var/spool/mail/root`. (Alternatively, mail can be delivered into users' home directories via `home_mailbox`.) The following manipulations are made to locally-delivered mail:

 * prepend a `From SENDER DATETIME` envelope header
 * prepend an `X-Original-To:` header
 * prepend an `Delivered-To:` header
 * prepend a `Return-Path:` header
 * prepend a `>` character to lines beginning with `From `
 * append an empty line

Also, the mailbox is locked while delivery is in progress; if an error occurs, the mailbox is truncated to its original length. Delivery is executed with the permissions of the recipient.

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== Local Routing ==

The local part of a destination address is extracted and casefolded to lowercase.

Frequently [[Postfix/Authentication|authentication]] features in a local delivery attempt.

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== Customization ==


=== Custom Delivery ===

A custom delivery command can be provided with `mailbox_command_maps` or `mailbox_command`.

In most cases, the command is executed with the recipient's permissions. If the recipient is `root`, a custom delivery command is executed with `default_privs`.



=== Qmail ===

For `qmail`-style mailboxes, the value of `mail_spool_directory` or `home_mailbox` must end in a forward slash (`/`).

{{{
home_mailbox = Maildir/
}}}

The following manipulations are made to locally-delivered `qmail`-style mail:
 * prepend a `Delivered-To:` header
 * prepend an `X-Original-To:` header
 * prepend a `Return-Path:` header



=== Forwarding ===

When attempting local delivery, `forward_path` is scanned for a `forward(5)` file (i.e. `~/.forward`). These looks like:

{{{
user@example.com        # anything after # is ignored
"|/path/to/examplemda"
}}}

Forwarded mail is sent as a new message with the `Delivered-To:` header, to prevent loops.

Note that the second line is only allowable if `allow_mail_to_commands` is set to:

{{{
allow_mail_to_commands = alias,forward,include
}}}

The default `alias,forward` disallows custom commands.



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