Postfix, virtual mailboxes and aliases: priority matters

Sometimes - either for work or leisure - I need to configure Linux servers, and also mail servers.

The '90s lovely logo of Postfix

postfix is a great software that I like to use for mailservers; in this post I want to describe you one feature that works in a counter-intuitive way.

In postfix you can define mailboxes by specifying in your /etc/postfix/main.cf:

virtual_mailbox_maps = hash:/etc/postfix/virtual_mailbox_maps

Official virtual MAILBOX example here

You can also specify aliases, e.g. mailboxes that directly forward to other mailboxes, by specifying:

virtual_alias_maps = hash:/etc/postfix/virtual_alias_maps

Official virtual ALIAS example here
Aliases are useful for example when you want to define a catch-all alias forwarding all mail to the postmaster address.

Priority matters!

However, what I dislike is the priority applied to both: aliases have higher priority than mailbox maps (yes, you've read right).

The first time I configured an alias I got all mail delivered to the catch-all address because I thought that - being less catchy - the catch-all addresses would have less priority.

What you need to do is instead add identity definitions to the aliases map, this way:

john@example.com   john@example.com
mary@example.com   mary@example.com
berry@example.com  berry@example.com
@example.com       postmaster@example.com

In above example of virtual_alias_maps, the last line is the catch-all line, while the other lines are inherent to mailbox maps defined in virtual_mailbox_maps.

Now tell me if that's not counter-intuitive, error-prone (because of the duplication) and less easy to mantain.