My company is using some external marketing company to do bulk email.
Let's say our domain is example.com. We have an mx record mail.example.com.
We were asked to setup A, MX and TXT records for news.example.com so they could
spam people from address firstname.lastname@example.org.
Everything works fine, except for sending test email to our users with email addresses @example.com.
I asked them if they have any logs and they said that they are getting this:
'Looks like we're getting a "5.4.6 (routing loop detected) / routing-errors" error message back on the deliveries sent to the example.co.uk contacts.
Please let me know if you have any further questions in the meantime.
I'm not sure what is going on, I don't even know if the emails are reaching our server at all (exchange 2007), I don't see anything in message tracking. I suspect a DNS problem but I maybe completely wrong.