Rebuild your exim.

cd /usr/local/directadmin/custombuild
./build update
./build set exim yes
./build set eximconf yes
./build set eximconf_release 4.5
./build set spamassassin yes
./build update
./build exim
./build exim_conf

Start, stop and restart the Exim mail server

Start Services:

/etc/init.d/exim start

or

service exim start

Stop Services:

/etc/init.d/exim stop

or

service exim stop

Restart Services

/etc/init.d/exim restart

or

service exim restart

Status of Exim service:

/etc/init.d/exim status

or

service exim status

or

systemctl status exim.service

Edit exim conf

vi /etc/exim.conf

Helpfiles for Exim

https://help.directadmin.com/?topic=17