Reply by mail - automatically remove attachments

Problem to solve

We're using S/MIME mail certificates for most of our mail communication. When replying to issues via mail the smime.p7s file is attached. This is cluttering our issue tracker and storage.

Proposal

It would be very helpful to have a possibility to ignore attachments from incoming mails by regex or disable them completely.

What does success look like, and how can we measure that?

Best thing would be a setting in gitlab.rb config file or the admin area.