To set up Google apps mail on your domain name, please do the following:
Firstly, you need to ensure your domain is pointed to our nameservers:
If the 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 Basic DNS tab.
Select an external email service from the Your email is pointing to: drop down list.
In the Location of service: field enter ASPMX.L.GOOGLE.COM and press the Point to service button.
Click Confirm to continue.
Click on the Advanced DNS tab.
Add the remaining MX records to configure Google apps mail on your domain name one at a time, pressing the Add new entry button between each record.
Once completed your MX records section will look like this: