Hi CS,
It is quite possible that one public domain has a reverse lookup record and the other does not. The main reason for having a reverse lookup record for a domain (in relation to mail) is so that recipient organisations that you send mail to can resolve your
mail servers public IP address to the domain name used in your email. This is a security configuration which helps the recipient mail servers define whether to accept your mail. If you use a domain name that does not have a reverse lookup record you may find
that when sending to some organisations your mail does not reach them.
Kind Regards
G,
