So new think to do: Quarantine addresses instead of deleting them and if for one provider most addresses fail don't give them another (maybe manually triggered) try later one.
(And if no such thing is detected deleted quarantined mail addresses.)
My guess is that how most email service providers handle this - they don't actually delete the email and just have a flag on it - bounced, complain, unsub. This way the list owner can run an export and see all the status code.
(And if no such thing is detected deleted quarantined mail addresses.)