Postfix/aliasing

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config files

user 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 <alias file>, e.g. 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.

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 = youraccount@anotherdomain.org
    • forwards all email addressed to invalid users to "youraccount@anotherdomain.org".

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