Yes, most likely! That is a common approach for 'soft bounces' in most list management systems (e.g. MailChimp).
The problem here is Gmail has been throwing out "NoSuchUser" errors which are an instant unsub in most systems because Gmail takes repeated delivery to non-existing addresses into account for deliverability purposes.
I'm extremely paranoid about email hygiene, tiny bounce rates and high delivery rates, so we aggressively unsubscribe troublesome addresses (often to the point of getting reader complaints about it) for many reasons beyond that, however.
That better describes what I was trying to say, yes. Reputation then affecting deliverability.
Over 80% of our subscribers use Gmail so to say I'm paranoid about maintaining a good record with them is an understatement ;-) Gmail is a huge weak link for us.
Logically you'd expect unsubscribe to only act after lots of bounces of this format when the address has been receiving mail fine before. It also seems reasonable not to trust such bounces for the entire domain for a while when this happens to lots of other addresses that have worked fine before. Not that I expect software currently works this way, but it does seem like a common sense thing to code in.
I mean, it's possible, but you'd need to queue up a day's worth of bounces, do the analysis, and then handle the bounces asynchronously later on to do that.
Most systems operate more immediately in isolation on individual addresses than that right now, because such analysis is generally not needed (until today, of course ;-)).
Mail agents already queue emails that bounce though; it's a matter of changing the conditions for when you retry and/or unsubscribe. I imagine you can do the analysis in real time too... just look at the bounce and see if it pertains to an email you sent to in the past, and if so, increment some rolling counter for that domain.
