On 4/6/20 3:03 PM, Rich Freeman wrote: > > More often than not, yes. The main exception I've seen are sites that > email you verification codes, such as some sorts of "two-factor" > implementations (whether these are really two-factor I'll set aside > for now). Many of these services will retry, but some just give up > after one attempt.
Greylisting suffers from one problem that unplugging the server doesn't: greylisting usually works on a triple like (IP address, sender, recipient), and can therefore continue to reject people who do retry, but retry from a different IP address. This occasionally affects things like Github notifications and requires manual intervention. (I would still recommend greylisting, personally, but it's a harder sell than that of foregoing a secondary MX.)
