This mornign a user tried to send an email to a customer and received the following error response:
CUSTOMERDOMAINNAME.com refected your message to the following e-mail addresses:
Customer Name (firstname.lastname@example.org)
customerdomainname.com gave this error:
<email@example.com>... Domain of sender OurUser@mail.OurDomain.com does not exist
Your message couldn't be delivered because you weren't recognized as a valid sender. Make sure your sending address is set up correctly and try to send the message again. If the problem continues, please contact your helpdesk.
Is this a problem on our end? We just migrated to this server over two weeks ago, but this is the first time we have had a problem sending outside of our domain.