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AT&T Postmaster Website

E-mail Error List

This page contains a list of possible solutions to the more frequent e-mail related errors experienced by non-AT&T customers attempting to send e-mail to AT&T Internet customers. Click on the error message for additional information.

421-failure in DNS look-up.
450 busy--Please try again later
521 <0.0.0.0> is blocked
550 [suspend] Mailbox currently suspended--Please contact correspondent directly.
550 [permfail] bellsouth.net requires valid sender domain
550 unauthorized interface for <0.0.0.0.>
550 <0.0.0.0.> blocked by ldap:ou=rblmx, dc=bellsouth, dc=net