Hi,
Thanks for your reply.
When I was using SENDMAIL to test, I was checking the /var/log/maillog files and it was getting rejected because the sender’s email didn’t exist.
So I set it to rewrite the domain for all addresses from the local pbx, with /etc/postfix/generic, for @freepbx.localdomain
Then my test message with SENDMAIL would work.
However when I made the test to leave a voicemail, the message wouldn’t go through and nothing would appear in the logs.