Postfix

About

Postfix is an open source mail transfer agent (MTA) for POSIX systems. It is fully supported by Webmin/VirtualMin and is part of the Dovecot stack.

Pages

• /fixing: diagnosis of installations that aren't working right

Files

• /main.cf
• /master.cf: formatted list of transport helper applications
• /mail.log (typically found in /var/log)

Internal Apps

• /aliases (reference)
• /cleanup (reference)
• /lmtp (reference)
• /local (reference)
• /pickup (reference)
• /qmgr (reference)
• /smtpd (reference)
• /transport (reference)
• /trivial-rewrite (reference))

User Applets

• /newaliases

Other Applets

These are installed as part of the postfix package; not sure how they should be classified:

/usr/bin: /mailq /newaliases - user utility /rmail /usr/lib: /postfix_groups.pl /sendmail

/usr/lib/postfix: /anvil /bounce /cleanup /discard /error /flush /fsstone /lmtp /local /master /oqmgr /pickup /pipe /post-install /postfix-files /postfix-script /postfix-wrapper /postmulti-script /proxymap /qmgr /qmqpd /scache /showq /smtp /smtpd /spawn /tlsmgr /trivial-rewrite /verify /virtual

/usr/sbin: /postalias /postcat /postconf /postdrop /postfix - core binary /postfix-add-filter /postfix-add-policy /postkick /postlock /postlog /postmap /postmulti /postqueue /postsuper /qmqp-sink /qmqp-source /qshape /rmail /sendmail /smtp-sink /smtp-source

Error Messages

• 503 5.5.1 Error: authentication not enabled
• Connect to private/dovecot-auth failed: No such file or directory

Other Subpages

• /flow: the flow of messages across the various helper programs that make up Postfix
• /SSL: Postfix and SSL

Notes

After making changes to the Postfix configuration files, you don't actually have to stop and restart Postfix to load the changes; you can just type (as root) "postfix reload".

aliases

To set up aliases, either edit the file specified by the alias_maps setting in main.cf (/etc/aliases by default) and then run newaliases (or postalias /etc/aliases) to update the database, or else use Webmin (Servers → Postfix Mail Server → "Mail Aliases" icon → "Create a new alias" link).

There is also a /etc/postfix/virtual file for aliases in virtual domains; it can be edited manually, but you need to run postmap /etc/postfix/virtual after modifying it.

Notes:

• Webmin seems to automatically run newaliases when you add or modify an individual alias, but not when you use it to edit the /etc/aliases file directly. Changes made to /etc/aliases will not take effect until the database is updated.
• Stopping and starting the postfix daemon does not update from the aliases file; you still have to run newaliases.
• see aliases for more information.

virtual users

By default, virtual aliases seem to get looked up only when email comes from the outside; locally generated emails are "returned" as undeliverable with the error message "Diagnostic-Code: x-unix; user unknown"

The following change in main.cf solves that problem –

• change: receive_override_options = no_address_mappings
• to this: receive_override_options =

– but creates a new one, in that externally-sourced messages are now delivered twice (or four times if addressed directly to a virtual user instead of a virtual alias).

Someone who understands the internal structure of postfix could probably figure out what this means (and how to fix it), but I'm still working on it.

catch-all

To set up a catch-all address, edit main.cf and set the following parameters:

• local_recipient_maps =
• luser_relay = whereToSend

The syntax for whereToSend is explained here.

Examples:

• luser_relay = $user@anotherdomain.org
  • forwards all email addressed to "invaliduser@firstdomain.org" to "invaliduser@anotherdomain.org"
• luser_relay = youraddress@anotherdomain.org
  • forwards all email addressed to invalid users to "youraddress@anotherdomain.org".

This page mentions some other parameters but neglects the ones above.

automatic BCC

To automatically BCC outgoing mail from any given set of users, set sender_bcc_maps in /main.cf to hash:/etc/postfix/sender_bcc. (In Webmin: BCC Mapping: Sender BCC mapping lookup tables)

Each line in the /sender_bcc file will contain the sender (which can be user@domain, user, or @domain), one or more blanks, then the recipient (which can be one address or multiple addresses separated by commas).

Example -- BCCs all mail sent by vbz.com users to an archive address:

@vbz.com archive2024@vbz.com

pages to index

Possibly useful pages:

• Setting Up Postfix As A Backup MX
• Postfix Address Rewriting
• trivial-rewrite (manpage)
• Postfix Configuration Parameters (includes /main.cf parameters)
• Postfix After-Queue Content Filter
• Group-Office Mailserver plugin: helps administer Postfix
• Mail server using Postfix and Dovecot on Gentoo Linux

Links

Official

• home page
• manpage

Reference

• Wikipedia