This article covers the SPF and DKIM authentication processes for MailChannels SMTP Relay and how they are managed in Valimail. While only one of the two authentication methods is required for an email to pass DMARC, our recommendation is to configure both whenever possible.

1) Add the following lines into the Exim configuration already in place (Our main cpanel guide should be used for the base configuration with MailChannels).

In the TRANSPORTSTART area at the end of the "mailchannels_smtp" transport section:

dkim_domain = $sender_address_domaindkim_selector = defaultdkim_canon = relaxeddkim_private_key = "/var/cpanel/domain_keys/private/${dkim_domain}"

2) The updated "mailchannels_smtp" transport section will look as follows when completed:

mailchannels_smtp:driver = smtphosts_require_auth = *tls_tempfail_tryclear = trueheaders_add = X-AuthUser: ${if match {$authenticated_id}{.*@.*}\{$authenticated_id} {${if match {$authenticated_id}{.+}\{$authenticated_id@$primary_hostname}{$authenticated_id}}}}dkim_domain = $sender_address_domaindkim_selector = defaultdkim_canon = relaxeddkim_private_key = "/var/cpanel/domain_keys/private/${dkim_domain}"

3) Ensure that you restart your mail server application after making changes to the configuration files so that your changes are implemented. Send some test traffic out through this server using your new DKIM key to ensure proper signing and readability with receivers.

You can also find the instructions on how to set up DKIM and SPF for MailChannels SMTP Relay, here.

You can find more detailed information on how to add a DKIM key in Valimail, here:

Once you establish that MailChannels SMTP Relay is an authorized sender for your domain, you will need to add the service in your Enabled Senders.

You will find more detailed information on how to add a service for your domain in Valimail, here:

Note: We encourage you to use the comment section for any useful information about your sending service, such as the name of the service owner, change request ticket numbers, etc.