The message cannot be delivered due to a configuration error on the server. Please contact your Administrator.
<firstname.lastname@example.org #5.3.0 smtp;553 5.3.0 <email@example.com>... Relaying denied>
When sending emails to a particular company the above error comes up. Emails to that specific company have problems. There is no pattern to the rejection. Some emails are rejected others not. Plain text emails, emails with small attachments, emails with large attachments. Some goes some doesn't. Is there anyway to troubleshoot and solve that problem.