Domain of sender address ... does not resolve

[Gordon Messmer]

Bill Davidsen wrote:
> I just did a new FC9 (fully updated) install, and it regularly rejects 
> outgoing mail with the subject error message. The address does resolve, 
> of course, so I'm not sure what it means instead of what it says.

Take the domain from the error message and run "host <domain>" on the 
command line, on the server that's rejecting the mail.

If you're sending mail from a host whose name does not resolve publicly, 
then the error that you're seeing is probably reported by mail servers 
outside your network that don't have access to your name servers.