The following problem is driving me nuts. I have setup a RH8 server with sendmail running. It has been setup in a small network, default gateway is 192.168.0.1.
a) Sending mail to local users -> no problem.
b) Sending mail to external users (valid email address like firstname.lastname@example.org
) -> mail is rejected, errror:
----- The following addresses had permanent fatal errors -----
(reason: 553 <email@example.com> unable to verify address)
c) Sending mail to a valid hotmail account (e.g. firstname.lastname@example.org
) -> success, mail is delivered without problem!!
Why is c) working and b) not? What is wrong in the setup?
I can ping any address in the outside world and also nslookup works fine.
E.g. nslookup -silent www-hccnet-nl gives: