649672e76e
Postfix has started outputting an error on startup that it can't parse the compatibility level 9999. Instead, just set the compatibility level to be identical to the current version, which seems to be the (new) intent for the compatibility level.
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at https://nixos.org/nixos and in the manual in doc/manual.