cPanel attempts to automatically detect whether or not our servers should be used to handle your e-mail, but in some cases may not detect the entries correctly. When attempting to send e-mail from your hosting account to your domain name using third party mail servers (such as Google Apps), the e-mails may be delivered locally instead of remotely. To check whether or not this is the case, and to correct the problem, please do the following;
1. Login to cPanel for the domain in question.
2. Click on the 'MX Entry' link/option in cPanel:
3. Take a look at the "Automatically Detect Configuration" line at the top. If it is set to Local, but you have custom and remote MX records set on your account, then cPanel has incorrectly determined that your mail should be handled locally. For reference, the following screenshot shows an account that is incorrectly determined to be handling mail locally:
3. To correct the problem and make cPanel route mail externally, ensure that 'Remote Mail Exchanger' is the enabled option
4. If the option "Remote Mail Exchanger" is not selected, click the radio button next to it and then click the 'Change' button.