Enhancement to deactivate dead emails

[shawnb61]

Following up on this thread:

The worst part about the failures would be the DOS that SMF would effectively start.  When mail queue started to pile up, it would keep trying to send emails and if you just upped your mail queue size thinking your more busy, your system would keep trying to send and it could result in other remote servers thinking your performing a some sort of attack and throttle or block you, which then you no longer can send any emails to that domain.  Running your own mail server, you learn that your domain and IP reputation are very important and you take care of everything to ensure you follow the rules, or the big giants will block your domain and don't care about unblocking you.

Reading this, I can't help but think that massive sites like SMF, which have decades worth of old registrations & emails, are sending a massive volume of email to nowhere...

I bet a lot of those are for email accounts that are no longer valid.

I wonder if, upon seeing a 5xx response code, we should inactivate email for that user - unset the opt-in flag.  And never even *try* to send to them again.

I bet the volume of email being sent would drop. 

A lot.

I suggest that if smtp mail, operating in this 'synchronous', non-relay mode, kicks back with a 5xx, that we opt that member out of email, & never attempt to email to them again.

Face it, that email is dead.  Why clog up your mail queue?

I'd opt out all of 5xx.  If they ever fix things (like full email boxes) they can opt back in.
https://www.mailersend.com/blog/smtp-codes

[Aleksi "Lex" Kilpinen]

I would still give it one attempt later, like a week later, because I have myself been locked out of a certain service completely because Microsoft had temporary issues with their email services and my email got blacklisted as "unreachable". Sucks I tell ya.

But otherwise, yeah - I do agree with the general idea.