I am going crazy about this error message.
for some of the domains, I am receiving this error message;
Reason: Remote SMTP Server Returned: 550 5.7.1 Unable to relay for firstname.lastname@example.org
I am using MailEnable on windows server 2008 r2. I have just migrated the whole domain from windows server 2003 and the e-mails worked just fine there.
What would solve this problem?