Fix some postfix startup issues after reboot

And enable ARC signing of emails

nix/modules/nixos/infrastructure/mailserver/dkim.nix

@@ -170,6 +170,15 @@ in
         }
       '';
     };
+    services.rspamd.locals."arc.conf" = lib.mkForce {
+      text = ''
+        enabled = true;
+        allow_username_mismatch = true;
+        domain {
+          ${lib.strings.concatStringsSep "\n " (lib.lists.map dkimSigningForDomain cfg.domains)}
+        }
+      '';
+    };
     services.postfix.config = {
       # Need to include this as I disabled the in built support for dkim signing
       # without this postfix won't forward the mails to rspamd to be signed.
@@ -183,10 +192,5 @@ in
         ReadOnlyPaths = domainKeyPaths;
       };
     };
-    systemd.services.postfix = {
-      unitConfig = {
-        ConditionPathExists = domainKeyPaths;
-      };
-    };
   };
 }

nix/modules/nixos/infrastructure/mailserver/ldap.nix

@@ -40,17 +40,24 @@ in
         uidAttribute = "uid";
       };
     };
-    systemd.services.dovecot2 = {
+    systemd.services = {
+      dovecot2 = {
         unitConfig = {
           ConditionPathExists = [ secretFile ];
         };
       };
+      postfix = {
+        unitConfig = {
+          ConditionPathExists = [ secretFile ];
+        };
+      };
+      postfix-setup = {
+        unitConfig = {
+          ConditionPathExists = [ secretFile ];
+        };
+      };
+    };
 
-    systemd.services.postfix = {
-      unitConfig = {
-        ConditionPathExists = [ secretFile ];
-      };
-    };
     khscodes.services.vault-agent.templates = [
       {
         contents = ''