We have sales@ and shop@ going to the same group mailbox in Discourse which is working great for us. However 1 minor issue that if someone mails both of those addresses, we get two copies of the exact same post. Is there some way discourse could drop duplicates like this?
Good question, but not sure how often this comes up. I think we would need a few more reports of it in the wild, otherwise maybe your mail server could detect and block this somehow?
I don’t think the MTA could do it; it’s job is to deliver mail, not de-dupe it. We could add a message ID cache in the app that kept a record of all “seen” message IDs for the past (say) 24 hours, and didn’t create a new topic if it would just be a dupe of an existing one. It’s not trivial work, though, and I’d say it’s a vanishingly rare occurance, so it’s probably best on the pr-welcome pile.
Comparison of Message-ID along with a double-check comparing hashes of the message bodies would certainly do the trick.