diff --git a/nixos/modules/services/mail/opensmtpd.nix b/nixos/modules/services/mail/opensmtpd.nix
index a870550ba50..1fabe2da45c 100644
--- a/nixos/modules/services/mail/opensmtpd.nix
+++ b/nixos/modules/services/mail/opensmtpd.nix
@@ -101,6 +101,12 @@ in {
       };
     };
 
+    systemd.tmpfiles.rules = [
+      "d /var/spool/smtpd 711 root - - -"
+      "d /var/spool/smtpd/offline 770 root smtpq - -"
+      "d /var/spool/smtpd/purge 700 smtpq root - -"
+    ];
+
     systemd.services.opensmtpd = let
       procEnv = pkgs.buildEnv {
         name = "opensmtpd-procs";
@@ -110,18 +116,6 @@ in {
     in {
       wantedBy = [ "multi-user.target" ];
       after = [ "network.target" ];
-      preStart = ''
-        mkdir -p /var/spool/smtpd
-        chmod 711 /var/spool/smtpd
-
-        mkdir -p /var/spool/smtpd/offline
-        chown root.smtpq /var/spool/smtpd/offline
-        chmod 770 /var/spool/smtpd/offline
-
-        mkdir -p /var/spool/smtpd/purge
-        chown smtpq.root /var/spool/smtpd/purge
-        chmod 700 /var/spool/smtpd/purge
-      '';
       serviceConfig.ExecStart = "${cfg.package}/sbin/smtpd -d -f ${conf} ${args}";
       environment.OPENSMTPD_PROC_PATH = "${procEnv}/libexec/opensmtpd";
     };