> there’s very little that can be verified if you strictly follow the RFC. That's not correct. You can reliably, completely validate all email addresses . . .

> there’s very little that can be verified if you strictly follow the RFC. That's not correct. You can reliably, completely validate all email addresses . . . by sending an email to them containing information that can be used to confirm the owner's identity. All together now: the MTA is the only source of "is it valid or not" for email addresses.