We have a server that uses postfix to forward emails for certain aliases to lists of people. Most of these people use a system (e.g. Gmail) that will reliably reject the emails if inboxes are full or they match malicious attachments, and postfix will then return a delivery failure message to Helpmonks.
When this happens, Helpmonks takes the failure email and creates a new conversation, which is then sent out to all users, causing a storm of emails. I’m sure Helpmonks already tries to identify bounce messages and treat them appropriately, but for some reason it’s not doing so in this case.
I’ve tried adding our server’s failure address to the Blacklist, but that doesn’t seem to work (possibly because it’s case sensitive but lower-cases the address?).