Type in the line below after you are remotely in the server.
/scripts/restartsrv service  
(replace service with the name of the service: exim, named, proftpd, httpd, etc.)

You can also restart mail services through the system. It depends on the OS you are using as to where the files are located. Many distributions are located in /etc/rc.d/init.d/
To restart this way you can use:
/etc/rc.d/init.d/service
(replace service with the name of the service: exim, named, proftpd, httpd, etc)

You can use the following command to list all the services that can be restarted by the system:
cat /etc/rc.d/init.d/

If the service fails after restarting, you should check the error log. For example, to check Apache’s error log, use:
tail /usr/local/apache/logs/error_log