Periodically I do attachment cleanup on old tickets:

• find old tickets (can do via REST)
• download attachments for archive (can do via REST)
• delete attachments from ticket (this enhancement request)
• add a note pointing to archived copied outside of mantis

It's really close to being a fully scripted process except for the delete part.

I've seen 2 cancelled PRs related to this topic. Hoping it can be revisited sometime soon.

TIA