I did a reboot for my system and exim stopped working. I'm not sure what went wrong…
tail /var/log/exim/main.log
2013-10-13 03:52:01 refused connection from localhost [127.0.0.1] (tcp wrappers)
2013-10-13 03:52:01 refused connection from localhost [127.0.0.1] (tcp wrappers)
2013-10-13 03:52:22 refused connection from localhost [127.0.0.1] (tcp wrappers)
2013-10-13 03:52:22 refused connection from localhost [127.0.0.1] (tcp wrappers)
2013-10-13 03:52:23 refused connection from localhost [127.0.0.1] (tcp wrappers)
2013-10-13 03:52:23 refused connection from localhost [127.0.0.1] (tcp wrappers)
2013-10-13 03:53:01 refused connection from localhost [127.0.0.1] (tcp wrappers)
2013-10-13 03:53:01 refused connection from localhost [127.0.0.1] (tcp wrappers)
2013-10-13 03:53:02 refused connection from localhost [127.0.0.1] (tcp wrappers)
2013-10-13 03:53:23 refused connection from localhost [127.0.0.1] (tcp wrappers)
cat /etc/hosts.allow
sshd:ALL
sendmail:ALL
mail:ALL
etc/init.d/exim status
exim (pid 35763) is running...
Best Answer
Section 8 of http://www.exim.org/exim-html-current/doc/html/spec_html/ch-building_and_installing_exim.html
Basically, change the "sendmail" to "exim".