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Hopefully this doesn't get used in some kind of registration flow in full since for example if you register with an aliased address, or you have a catchall addr
by sdfhbdf 6y ago
Hopefully this doesn't get used in some kind of registration flow in full since for example if you register with an aliased address, or you have a catchall address or email is just proxied the SMTP checks would fail.
- huhtenberg 6y agoWhy would they fail? It opens an SMTP connection and runs through the handshake. If this fails then, it will fail with a real delivery just the same. It's still a bad test to do, but for other reasons.
- edoceo 6y agoWhat are the other reasons? On signup for my app we validate like this, with MX and SMTP check - before sending a account verify message
- huhtenberg 6y agoSMTP checks need to be run from the actual mail server/cluster that will be sending emails, using the exact same EHLO greeting, etc. Otherwise you may get both false positives and negatives due to IP blocks and mail header filters on the receiving end. That's without getting into timeouts and remote-side enforced TLS.