Postfix

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Revision as of 14:24, 9 August 2021 by Woozle (talk | contribs) (→‎aliases)
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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

Internal Apps

User Applets

Other Applets

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

Error Messages

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 –

– 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:

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:

Links

Official

Reference

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