smtp codes
Deliverability folks from a few different email sending platforms have mentioned seeing a new bounce from Comcast, in response when trying to mail certain comcast.net subscribers:550 5.2.0 – Account Closed, Please RemoveWhat does it mean? Nobody home! That’s a dead account. The user is an ex-parrot. Send them no more mail. Seems simple enough to me, but people always have questions about this kind of thing, so I figured I’d share it with you all.And of course, there’s still this usual bounce:550 5.1.1 – Not our CustomerMeaning that’s not a valid Comcast subscriber address, either. Same deal, nobody home. It likely means nobody was ever home at that address, but even if I’m slightly wrong about that, the net here is the same; time to stop mailing that address.And then there’s also a slightly rarer 4xx bounce that looks like this:450 4.2.0 – Recipient temporarily unavailableThose ones, you should retry per
If you want to learn more about SMTP response codes and error messages, here’s a couple of resources you’ll want to check out and bookmark for future reference. First, here’s John Porrini from SocketLabs: 21 SMTP Response Codes That You Need To Know.And after you’ve checked that out, you’ll want to bookmark the SMTP FIELD MANUAL: A collection of raw SMTP error codes spotted in the wild from Postmark. Very useful to try to understand what kind of rejects (bounces) certain mailbox providers will send back and sometimes it has come in handy when I can’t access to a client’s actual bounce message, so I can review what common ones that particular mailbox provider sends, and develop a thoery of what might have happened, based on that.