How to inform users that they don’t have permission to access redmine if the users submit an issue via sending email?

Added by rony f 4 days ago

we have deployed a redmine and already used creating issue via email feature , but now we have a question, currently, we are using LDAP for redmine authentication , but not all users' account are created, so if some users to create issue via sending email but they don't have permission, then how can we return a mail to the user to inform they need to register their AD account and get permission? can we set up in bitnami redmine or need plugins ? please help to guide.