nixos-mailserver/docs/migrations.rst

Migrations
==========

With mail server configuration best practices changing over time we might need
to make changes that require you to complete manual migration steps before you
can deploy 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 mail server. 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;