I have a customer that regularly sends mail to adventurecenter.org. Messages are bouncing back saying is a routing error with two servers and to contact the administrator (me). I've looked at the MX record for adventure center and get the following from MXtoolbox:
10 <blank> 192.168.75.11
10 mail.adventurecenter.org 126.96.36.199
I went in to nslookup on my server and did a set q=mx to see what my server is seeing, which is:
MX preference = 10, mail exchanger = <root>
MX preference = 10, mail exchanger = mail.adventurecenter.org
I believe the dual entries in the MX record are causing the mail problems. Is there a way in Exchange or DNS to hardwire to the correct hostname?