To set up a DKIM (DomainKeys Identified Mail) record on your domain name, please do the following:
Before you begin, you need to ensure your domain is pointed to our nameservers:
If your domain is not pointed to the 123-reg nameservers, you will be unable to manage them from the 123-reg control panel.
For more information on changing your nameservers please view the following article:
How do I change the nameservers for my domain name?
Please note: It will take between 24-48 hours for the new DNS records to become active
In the Domain names section, select the relevant domain name in the drop-down list and click on the Manage button.
Scroll down to the Advanced Domain Settings section and click on the Manage DNS (A, MX, CNAME, TXT) link.
From the Advanced DNS tab.
Select TXT/SPF from the Type drop down list in the Add new entry section.
In the Hostname field enter the hostname you have been provided with. For example sl._domainkey
In the Destination TXT/SPF field enter the DKIM record that is required.
Click on the Add new entry button to save the new record.