I have set up an alias in /etc/mail/aliases like this:
This relay DOES work when I telnet to example.com 25 and send mail to firstname.lastname@example.org (where example.com is my domain); it indeed turns up in email@example.com inbox.
Also mail sent from my server at example.com is generally deliverable to this same email address, firstname.lastname@example.org.
HOWEVER, the relay DOES NOT work when I send mail from email@example.com to firstname.lastname@example.org, expecting it to be relayed back to email@example.com.
The mail.log shows it being received and sent just fine, so I guess it is being blocked by gmail for some reason. Why though? As I said, gmail generally does except mail from this server.