The following error appears when trying to send an email:
The email address entered is invalid, please correct the email address and try again
Wireshark trace shows:
550 5.7.1 Unable to relay for <email address>
Service Closing transmission channel
The mail relay was badly created.
Email Administrator needs to fix this in the Exchange Server. Refer to the links noted in the Additional Information section for further details on the steps in the Exchange Server.