treewide: remove overly broad with cfg

Makes it really hard to follow references and we were being explicit in
most places already anyway.

mail-server/networking.nix

@@ -20,21 +20,19 @@ let
   cfg = config.mailserver;
 in
 {
-  config =
-    with cfg;
-    lib.mkIf (enable && openFirewall) {
+  config = lib.mkIf (cfg.enable && cfg.openFirewall) {
 
-      networking.firewall = {
-        allowedTCPPorts =
-          [ 25 ]
-          ++ lib.optional enableSubmission 587
-          ++ lib.optional enableSubmissionSsl 465
-          ++ lib.optional enableImap 143
-          ++ lib.optional enableImapSsl 993
-          ++ lib.optional enablePop3 110
-          ++ lib.optional enablePop3Ssl 995
-          ++ lib.optional enableManageSieve 4190
-          ++ lib.optional (certificateScheme == "acme-nginx") 80;
-      };
+    networking.firewall = {
+      allowedTCPPorts =
+        [ 25 ]
+        ++ lib.optional cfg.enableSubmission 587
+        ++ lib.optional cfg.enableSubmissionSsl 465
+        ++ lib.optional cfg.enableImap 143
+        ++ lib.optional cfg.enableImapSsl 993
+        ++ lib.optional cfg.enablePop3 110
+        ++ lib.optional cfg.enablePop3Ssl 995
+        ++ lib.optional cfg.enableManageSieve 4190
+        ++ lib.optional (cfg.certificateScheme == "acme-nginx") 80;
     };
+  };
 }