
Change the default SMTP port to `25`, to better match the default address `localhost`. This gets rid of some error outputs in the test, where it fails to connect to localhost:465. Also, don't enable postfix by default unless it's actually useful to us.
*** 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.