A backlisting options would make sense to exclude senders from being able to create issues or comments via email.
if a blacklisted senders sends an email, the email should be blocked (not processed) and a notification email should be sent to an admin. (see Mail handler Forward Email attribute).
Example use case: Internal users must fill all required fields when an issue is created. They should not be able to send an email to create an (incomplete) issue.
Seems like a good solution. Maybe regexps are a little difficult for the admins which have no programmer experience, but with good help texts and examples this will be a really valuable function.
I have added a screenshot of the field with explanation texts you will receive. Is it clear and informative enough?
Released as version 5.5
Great! I was just wondering about that config due to our SPAM Mails.