I suggest writing a rule to send an auto-reply, like this: https://datatracker.ietf.org/doc/draft-ietf-mailmaint-wrong-recipient/ https://datatracker.ietf.org/d

I suggest writing a rule to send an auto-reply, like this: https://datatracker.ietf.org/doc/draft-ietf-mailmaint-wrong-recipient/ https://datatracker.ietf.org/doc/draft-ietf-mailmaint-wrong-... That document tweaks the unsubscribe to say "unsubscribe because wrong recipient", most parsers won't notice the "because".