I have my sendmail.cf file configured to send local mail and to receive external mail to local users. So sending mail from the server to the external world works fine, but the other way around does not... I get an error e-mail saying:
Delivery to the following recipient failed permanently:
Technical details of permanent failure: Google tried to deliver your message, but it was rejected by the recipient domain. We recommend contacting the other email provider for further information about the cause of this error. The error that the other server returned was: 550 550 5.7.1 firstname.lastname@example.org... Relaying denied (state 14).
Also I can't find logs in /var/log, all I see is this binary file in /var/log/mail/statistics