Some time your exim refuses to deliver email giving retry time out error even if you can telnet to the mail server for your domain on port 25 with no problem.
In this case first try restarting exim. if it still don't work then go to /var/spool/exim/db and rename the files "retry" and "ratelimit" and then restart Exim again and you will see all your emails being delivered to to your domain.
