nixos-mailserver/docs/migrations.rst

Migrations
==========

With mailserver configuration best practices changing over time migrations are
a required step to complete before updating to a new version of NixOS
mailserver.

The initial `mailserver.stateVersion` value should be copied from the setup
guide that you used to initially set up your mailserver. If in doubt you can
always initialize it at `1` and walk through all assertions, that might apply
to your setup.

NixOS 25.11
-----------

This option was introduced in the NixOS 25.11 release cycle, in which case you
can safely initialize its value at `1`.

:: code-block: nix

   mailserver.stateVersion = 1;