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Besides not having to deal with the overhead of running your own email serves, Google Email also has support to 2-Factor Mobile SMS authentication through Web Browsers and a form of OTP when connecting devices or email clients. Consider turning this on for high security accounts.
Google Apps Control Panel
Log into your Google Apps making sure to replace earth.com to your actual domain name,
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At this point you will be given instructions to update your DNS provider with the CNAME record.