
Absolute path is required when one has such postfix configuration where he/she needs to specify the actual (real) path to active dovecot config. Without this commit applied, the dovecot is running in such way: /nix/store/hashAAA-dovecot-ver/sbin/dovecot -F -c /nix/store/hashBBB-dovecot2.conf and postfix can't be aware of the value of "hashBBB" via services.postfix.extraConfig = '' ... ''; (it can only be aware of "hashAAA" with ${pkgs.dovecot} parameter) Also enable Restart on-failure. Edit: set RestartSec to 1s
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at http://nixos.org/nixos and in the manual in doc/manual.