diff --git a/nixos/modules/services/mail/exim.nix b/nixos/modules/services/mail/exim.nix
index 892fbd33214..8927d84b478 100644
--- a/nixos/modules/services/mail/exim.nix
+++ b/nixos/modules/services/mail/exim.nix
@@ -67,6 +67,13 @@ in
         '';
       };
 
+      queueRunnerInterval = mkOption {
+        type = types.str;
+        default = "5m";
+        description = ''
+          How often to spawn a new queue runner.
+        '';
+      };
     };
 
   };
@@ -104,7 +111,7 @@ in
       wantedBy = [ "multi-user.target" ];
       restartTriggers = [ config.environment.etc."exim.conf".source ];
       serviceConfig = {
-        ExecStart   = "${cfg.package}/bin/exim -bdf -q30m";
+        ExecStart   = "${cfg.package}/bin/exim -bdf -q${cfg.queueRunnerInterval}";
         ExecReload  = "${coreutils}/bin/kill -HUP $MAINPID";
       };
       preStart = ''