Relaying denied, Sendmail 8.12.9
 

We have Linux 7.2 an sendmail 8.11.3. All users were able to send to internal und to external recipients if there IP-Adreess is known by our DNS.

Now I have cloned the disk and on the clone I installed sendmail 8.12.9. I am using the same sendmail.cf like I used with sendmail 8.11.3. Now no user is able send to an external recipient (all others intern -> intern, extern -> intern is possible). In /var/log/messages I read "Relaying denied". What is the mistake?

Triple check to make sure that your internal users IPs are resolving to your internal domain. Or, just put their ip block in /etc/mail/relay-domains.

If the subnet is 192.168.1.0/24, then put 192.168.1 in that file. That will do the trick. I think you ahve to restart sendmail for it to see the changes.