It would be great to have reply detection to stop follow ups or change campaign once a contact respond. So once you start dealing with a contact directly they stop receiving further marketing emails and follow-ups until further notice. As it stands many people (myself included) are spending hours each week updating prospect lists and managing campaigns as contacts take action on an email.
This is done perfectly by woodpecker.co - “Once a reply to any of your emails comes in, even from another email address, the follow-up sequence planned for the prospect is stopped automatically.”
This would need to check an inbox ever 10-30 mins.
Detect second email addresses encase of somebody replying for an alternate account
Distinguish between auto-replies.
Update contact details to take action (stop/switch sequence)
it has been discussed previously here - https://github.com/mautic/mautic/issues/425