Configure relay host in cPanel Exim to set up a mail server for sending outgoing mail to a specific server that will handle the delivery to the recipients with SMTP relay or smart host, with the help of our cPanel & WHM Support Services at Bobcares.

Configure SMTP relay host in cPanel Exim

The simple Mail Transfer Protocol (SMTP) process allows users to send, relay, and monitor outgoing emails. An SMTP relay service also commonly known as an SMTP gateway service takes this a step further by allowing to send more transaction and marketing-related emails

• A user creates a message in a Mail User Agent (MUA) such as Roundcube from the cPanel.

• Here the MUA passes the message to a Mail Submission Agent (MSA), which then hands it to a Mail Transfer Agent (MTA).

• Messages travel through multiple MTAs before they finally reach the Mail Delivery Agent (MDA) and the recipient’s inbox.

The SMTP “language” MTAs use to communicate with each other. They accept incoming emails, next queue them, and then send them to another MTA or a mail delivery agent.

Prerequisites

• Note down the hostname of the SMTP server which is going to relay the mail for your mail server.

• No authentication is required for SMTP relay server.

• Login details of WHM ready.

Step 1: Login on WHM

Login to WHM, by accessing https://host_ip:2087 (replace host_ip with the IP address/hostname of your server).

Step 2: Add SPF including host

From WHM navigate to Main >> Service Configuration >> Exim Configuration Editor >> Search for “SPF include hosts for all domains on this system” and then update the setting from “None” to “spf.smtprelay.snel.com”. Click on “Save” at the bottom.

Step 3: Configure the MTA

On the same page Exim Configuration Editor, click on the Advanced Editor button and search on the page for “Section: POSTMAILCOUNT” and add the below details:

smart_route:
driver = manualroute
domains = ! +local_domains
ignore_target_hosts = 127.0.0.0/8
transport = remote_smtp
route_list = * smtprelay.snel.com::587
no_more

If the “Section: POSTMAILCOUNT” is not available then proceed to next step 4, or else proceed to step 5.

Step 4: IF “Section: POSTMAILCOUNT” is not available

On the Exim Configuration Editor page search for “Section: ROUTERSTART” and add below settings:

smart_route:
driver = manualroute
domains = ! +local_domains
ignore_target_hosts = 127.0.0.0/8
transport = remote_smtp
route_list = * smtprelay.snel.com::587
no_more

Step 5: Save changes

Click on the “Save” button at the bottom of the page for the changes to reflect, and later restart the mail server to apply the new configuration.

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Conclusion

To conclude, you have successfully set up an SMTP relay for your mail server from Configure relay host in the cPanel Exim article.