diff --git a/nixos/modules/services/mail/mailman.nix b/nixos/modules/services/mail/mailman.nix
index 0c9b38b44b2..f36abadf9d7 100644
--- a/nixos/modules/services/mail/mailman.nix
+++ b/nixos/modules/services/mail/mailman.nix
@@ -313,7 +313,8 @@ in {
     systemd.services = {
       mailman = {
         description = "GNU Mailman Master Process";
-        after = [ "network.target" ];
+        after = [ "network.target" ]
+          ++ lib.optional cfg.enablePostfix "postfix-setup.service";
         restartTriggers = [ config.environment.etc."mailman.cfg".source ];
         wantedBy = [ "multi-user.target" ];
         serviceConfig = {
diff --git a/nixos/modules/services/mail/postfix.nix b/nixos/modules/services/mail/postfix.nix
index 23d3574ae27..da14b6eef7e 100644
--- a/nixos/modules/services/mail/postfix.nix
+++ b/nixos/modules/services/mail/postfix.nix
@@ -723,23 +723,10 @@ in
         { ${setgidGroup}.gid = config.ids.gids.postdrop;
         };
 
-      systemd.services.postfix =
-        { description = "Postfix mail server";
-
-          wantedBy = [ "multi-user.target" ];
-          after = [ "network.target" ];
-          path = [ pkgs.postfix ];
-
-          serviceConfig = {
-            Type = "forking";
-            Restart = "always";
-            PIDFile = "/var/lib/postfix/queue/pid/master.pid";
-            ExecStart = "${pkgs.postfix}/bin/postfix start";
-            ExecStop = "${pkgs.postfix}/bin/postfix stop";
-            ExecReload = "${pkgs.postfix}/bin/postfix reload";
-          };
-
-          preStart = ''
+      systemd.services.postfix-setup =
+        { description = "Setup for Postfix mail server";
+          serviceConfig.Type = "oneshot";
+          script = ''
             # Backwards compatibility
             if [ ! -d /var/lib/postfix ] && [ -d /var/postfix ]; then
               mkdir -p /var/lib
@@ -777,6 +764,24 @@ in
           '';
         };
 
+      systemd.services.postfix =
+        { description = "Postfix mail server";
+
+          wantedBy = [ "multi-user.target" ];
+          after = [ "network.target" "postfix-setup.service" ];
+          requires = [ "postfix-setup.service" ];
+          path = [ pkgs.postfix ];
+
+          serviceConfig = {
+            Type = "forking";
+            Restart = "always";
+            PIDFile = "/var/lib/postfix/queue/pid/master.pid";
+            ExecStart = "${pkgs.postfix}/bin/postfix start";
+            ExecStop = "${pkgs.postfix}/bin/postfix stop";
+            ExecReload = "${pkgs.postfix}/bin/postfix reload";
+          };
+        };
+
       services.postfix.config = (mapAttrs (_: v: mkDefault v) {
         compatibility_level  = pkgs.postfix.version;
         mail_owner           = cfg.user;