I am having an intermittent problem with messages bouncing back. After doing some research I have found that my Exchange server is attempting to connect to server that has the A record for the domain but does not connect to the MX record of the domain.
I try to send to email@example.com and get a bounce back of “550 not local host abc.com, not a gateway>”. I check the Event log and find Event ID 7004 telling the following:
This is an SMTP protocol error log for virtual server ID 1, connection #8829. The remote host "220.127.116.11", responded to the SMTP command "rcpt" with "550 not local host abc.com, not a gateway ". The full command sent was "RCPT TO:<firstname.lastname@example.org> ". This will probably cause the connection to fail.
I then look up the MX records for abc.com and find the following:
abc.com. MX IN 28800 mail1. abc.com. [Preference = 10]
abc.com. MX IN 28800 mail2. abc.com. [Preference = 30]
mail1.abc.com. A IN 28800 18.104.22.168
mail1.abc.com. A IN 28800 22.214.171.124
I then look up the A records for abc.com and find the following:
abc.com. A IN 28800 126.96.36.199
Bascially, my mail server is connecting to the A record of the domain vs. the MX record of the domain. In most cases, I can resend the same message later to the same email address with no problem. This problem does not happen all of the time.
Why would this happen? How can I correct the problem.