SMTP servers are able to reply whether a user exists, and some still do. Your ow... | Hacker News

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emteycz on Jan 30, 2022 | parent | context | favorite | on: Did I just lose half a million dollars?

SMTP servers are able to reply whether a user exists, and some still do. Your own server will send you a "undeliverable" message if it receives a negative reply.

capableweb on Jan 30, 2022 [–]

Yes, but that's different. That checks if the user exists, not if the person behind the user actually has access to that user.

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