To configure CPanel to utilize the Sendmetric smarthost you will need to login to WHM and go to the Exim Configuration Manager. Then select the Advanced Editor and make the changes below.
Before doing this make sure to go the Backup tab and save a backup copy of your Exim configuration in case you have problems.
Section: AUTH
Go to this section in the advanced editor and enter the information below in the text area. Make sure to replace the username and password with the SMTP user that you added. For more information on adding a user see the Getting Started Guide.
#SENDMETRIC_AUTHENTICATORS_START
sendmetric_login:
driver = plaintext
public_name = LOGIN
client_send = : username : password
#SENDMETRIC_AUTHENTICATORS_STOP
Section: POSTMAILCOUNT
In this section add the information below in the text area:
#SENDMETRIC_POSTMAILCOUNTSTART
remoteserver_route:
driver = manualroute
transport = sendmetric_smtp
domains = !+local_domains
route_list = * smtp.sendmetric.com::25 randomize byname
#SENDMETRIC_POSTMAILCOUNTSTOP
Section: TRANSPORTSTART
In this section add the information below in the text area:
#SENDMETRIC_TRANSPORTSTART
sendmetric_smtp:
driver = smtp
hosts_require_auth = *
tls_tempfail_tryclear = true
headers_add = X-AuthUser: ${if match {$authenticated_id}{.*@.*}\
{$authenticated_id} {${if match {$authenticated_id}{.+}\
{$authenticated_id@$primary_hostname}{$authenticated_id}}}}
#SENDMETRIC_TRANSPORTSTOP
Once you make the changes above, scroll to the bottom of the advanced editor and click 'Save'. Verify the Exim service restarts correctly and you are ready to use the Sendmetric service.