Restrict mailbox creation depending on plan

dashboard/src/views/UsersView.vue

@@ -148,8 +148,8 @@ function onPasswordReset(user) {
 }
 
 function onEditOrAddUser(user = null) {
-  if (features.value.userMaxCount <= users.value.length) subscriptionRequiredDialog.value.open();
-  else userDialog.value.open(user);
+  if (user || features.value.userMaxCount > users.value.length) userDialog.value.open(user);
+  else subscriptionRequiredDialog.value.open();
 }
 
 const invitationDialog = useTemplateRef('invitationDialog');