Emails are not DKIM-signed when sending with a smarthost

Symptoms 

You may find that emails sent via smarthost are not DKIM-signed despite having a valid DKIM record. 

Description 

This typically occurs when the smarthost is not configured to send emails with DKIM.

Workaround

1. Connect to your server via SSH as the root user or use "WHM / Server Configuration / Terminal".

2. Open /etc/exim.conf.local using your preferred command-line text editor:

How to edit a file on command-line

3. In your smarthost configuration, search for the following line:

transport = remote_smtp

4. Change this to the following:

transport = dkim_remote_smtp

5. Save and close the file.

6. Run the following scripts to load the change:

/scripts/buildeximconf 

/scripts/restartsrv_exim

Email should now be DKIM-signed when using the smarthost.