550 Requested action not taken: mailbox unavailable or not local

Have set up a small website for a client however contact form submissions a开发者_Go百科re not getting through to their email address.

The bounce back has this message attached:

550 Requested action not taken: mailbox unavailable or not local

It sends without issue to my email address and others but can't get to any on their domain.

Client's IT guy is a bit clueless so I'm unsure how he's configured the mail server?

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You're probably sending the emails to an incorrect email address, or possible the emails are being sent to the http server for the domain (or similar) but the SMTP server is hosted elsewhere.

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Found the problem, was due to webserver having max entries which meant it was trying to send mail to itself rather than the external mail server.

Deleting DNS entries fixed the problem.