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

#3 Dovecot mail directory migration

The way the Dovecot home directory for login accounts were previously set up resulted in shared home directories for all those users. This is not a supported Dovecot configuration.

To resolve this we migrated the home directory into the individual domain/localpart subdirectory below the mailserver.mailDirectory.

But since this now overlaps with the location of the Maildir, it must be migrated into the mail/ directory below the home directory. And while the LDAP home directory is not affected we use this migration to keep the Maildir configurations of LDAP users in sync with those of local accounts.

This is a big step forward, since we can now more cleanly colocate other data directories, like sieve in the home directory, which in turn simplifies backups.

This migration is required for every configuration.

For remediating this issue the following steps are required:

1. Copy the migration script script to your mailserver and make it executable:

   wcurl https://gitlab.com/simple-nixos-mailserver/nixos-mailserver/-/raw/master/migrations/nixos-mailserver-migration-03.py
   chmod +x nixos-mailserver-migration-03.py
   

2. Stop the dovecot2.service.

   systemctl stop dovecot2.service
   

3. Create a backup or snapshot of your mailserver.mailDirectory, so you can restore should anything go wrong.

4. Run the migration script under your virtual mail user with the following arguments:

   • --layout default unless useFSLayout is enabled, then --layout folder

   • The value of mailserver.mailDirectory, which defaults to /var/vmail

   The script should be run under the user who owns the mailDirectory. If run as root it will try to switch into the appropriate user by itself.

   The script will not modify your data unless called with --execute.

   Example:

   ./nixos-mailserver-migration-03.py --layout default /var/vmail
   

5. Review the commands. They should be

   • create a mail directory for each accounnt,

   • move maildir contents from the parent directory into it,

   • suggest removal of files that do not belong to the maildir

     • their removal is not mandatory and the script will not remove them when called with --execute

     • review these items carefully if you want to remove them yourself

   • remove obsolete files from the old home directory location

6. Rerun the command with --execute or run the commands manually.

7. Update the mailserver.stateVersion to 3.

#2 Dovecot LDAP home directory migration

The Dovecot configuration for LDAP home directories previously did not respect the mailserver.mailDirectory setting.

This means that home directories were unconditionally located at /var/vmail/ldap/%{user}.

This migration is required if you both:

• enabled the LDAP integration (mailserver.ldap.enable)

• and customized the default mail directory (mailserver.mailDirectory != "/var/vmail")

For remediating this issue the following steps are required:

1. Stop dovecot2.service.

2. Move /var/vmail/ldap below your m̀ailserver.mailDirectory.

3. Update the mailserver.stateVersion to 2.

#1 Initialization

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

mailserver.stateVersion = 1;