I am trying to set up a MTA with exim4. I am able to install and configure it to send mail out, but can't send any mail. I type mail -s "Hello" firstname.lastname@example.org
(just for posting), it looks like it is sent but I can't never receive any mail from that server.
I even send it to my yahoo account but the email never arrives.
Are all the other mail servers not accepting any mail from servers that are not registered?
Please help me understand what's wrong. Thank you.