I am trying to change the primary SMTP address. I have multiple domains on the exchange server and would like to change the primary from domain1.com to domain2.com. I have updated the recipient policy to do this and checked the changes have propagated. But when I try to send an email I get the following NDR:
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<server.domain.local #5.5.0 smtp;550 <email@example.com>... Not permitted>
If I change it back to the original domain, mail sends again.