resolving email addresses

[James D. Parra]

Hello,

I tried to test a new MailScanner/Sendmail setup we have, but from the
outside a telnet session to the mail server will give an error of, "Domain
of sender address "joesomebody at realdomain.com" doesn't resolve. However, I
can ping the domain from the server.

Any clues on how to fix this?

Thank you in advance.

James