nixos/services/nginx_vHosts/mail.nix

{
  config,
  lib,
  ...
}:
with lib;
  {
    vHost =
      if config.mailserver.enable
      then {
        serverName = config.mailserver.fqdn;
        enableACME = true;
        forceSSL = true;
      }
      else {};
  }
  .vHost