Accepting domain literals on a mail server
Q I have a Red Hat 8.0 server with one primary domain. A friend of mine recommended I check out www.DNSreport.com, which performs a variety of useful tests on the DNS records as well as the server itself. Everything went through fairly well but my domain failed on one test. The following is from DNSreport.com:
ERROR: One or more of your mailservers does not accept mail in the domain literal format
(email@example.com). Mailservers are required RFC1123 5.2.17 to accept mail to domain literals for any of its IP addresses.
I’m not sure how to go about fixing this problem – or even if it’s worth fixing.
A RFC1 123 requires the ability to use domain literals (ie using [s and ]s) tospecify the IP address of a mail server, and thus bypass normal DNS mechanisms. For security and for spam prevention reasons, not all mail servers are configured with it enabled by default. If you would like to have your Sendmail daemon server accept mail sent to it in this way, you can add a line containing only [10.10.10.10] to /etc/mail/local-host-names where 10.10.10.10 is the IP address you would like sendmail to listen to.