I have user trying to send emails to
Delivery has failed to these recipients or distribution lists:
Your message wasn't delivered because of security policies. Microsoft
Exchange will not try to redeliver this message for you. Please provide the
following diagnostic text to your system administrator.
The following organization rejected your message: flph259.prodigy.net.
Sent by Microsoft Exchange Server 2007
Diagnostic information for administrators:
Generating server: our transport server
flph259.prodigy.net #550 5.7.1 Connections not accepted from servers without
a valid sender domain.flph259 Fix reverse DNS for x.x.x.x ##