This probably only works for a few percent of mail servers these days, most will accept any RCPT TO address, wait for the DATA block and then black hole or reply with an error via a separate outbound message. Specifically done to permit more filtering (anti-spam etc.) and to /prevent/ these sorts of validity checks as they are popular with spammers (can't think why :))
For further actions, you may consider blocking this person and/or reporting abuse
We're a place where coders share, stay up-to-date and grow their careers.
This probably only works for a few percent of mail servers these days, most will accept any RCPT TO address, wait for the DATA block and then black hole or reply with an error via a separate outbound message. Specifically done to permit more filtering (anti-spam etc.) and to /prevent/ these sorts of validity checks as they are popular with spammers (can't think why :))