I have an exchange 2010 email server that has multiple domains. the main domain that the server was created internally is with the main AD mail.xyz.com. However I have another OU that has a domain of abcd.com. That email sends and receives okay through out the internet. However some email servers drop the emails because of mismatch smtp banners and reverse lookup dns. I have the reverse lookup dns resolved but when I test my email server on mxtoolbox I get the smtp banner failed and I see the banner with the wrong domain. The receive connector allows the enter to be null or just host name but I cannot change the FQDN to a domain that I would like nor could I define more that one domain.
Does this mean that I will always be plagued with email servers that reject my emails?
Most of the servers accept my emails, it just looks like some of the ones that check for relaying or think spam reject my emails.