See below for some (or all) of the things that need doing, depending on the extent you want to use it.

1. Set up your MX records (to receive email) to the following:
   Note: see our instructions on how to edit MX entries here.
   ​

   Name/Host/Alias	Time to Live	Record Type	Priority	Value/Answer/Destination
   Blank or @	3600	MX	1	ASPMX.L.GOOGLE.COM.
   Blank or @	3600	MX	5	ALT1.ASPMX.L.GOOGLE.COM.
   Blank or @	3600	MX	5	ALT2.ASPMX.L.GOOGLE.COM.
   Blank or @	3600	MX	10	ALT3.ASPMX.L.GOOGLE.COM.
   Blank or @	3600	MX	10	ALT4.ASPMX.L.GOOGLE.COM.

2. Set up your CNAME records (to use the calendar, etc.) 

3. Remove the 'localdomains' entry (if you are using a web-based email form on your site we can do this for you!)