This is a Tutorial of how to enable Google apps to work on your domain name. What I will be covering is how to ONLY setup EMAIL and NOT WEBHOSTING. Why NOT hosting? Because almost all of you have a descent site now and will not benefit from moving your website.
GoTo http://www.google.com/a/cpanel/domain/new and sign up for an account
If you already have a Gmail email you can use this account as the primary account to setup all the settings, or you can sign up for a new Gmail account
Setup Domain Details.
Your Name, Your Organization, how many users, etc…
Setup the Primary Master account
Setup What applications you want
For most of you your just going to want to setup Email and Calendar
The most difficult part is the Changes to DNS you will have to make.
These next steps below are copied directly from Google. They maybe a little different depending on what domain host you use.
1. Sign in to your domain hosting company’s website using the username and password associated with your domain.
2. Navigate to an MX record maintenance page. MX records are special DNS (Domain Name Service) records, and are often located under sections titled “DNS Management,” “Mail Server Configuration,” or “Name Server Management.” You may need to turn on advanced settings to allow editing of these MX records. DotNet Panel users click on Domains, it will list you all of your domain click on desired domain for which you want to configure google apps and then click on "Dns Zone Editor" button and create MX records here.
3. Delete any existing MX records before entering new MX records.
4. For each MX record, enter information according to the entries in the following table.You may not be allowed to enter the priority values exactly as they appear in the table below; in that case, simply ensure that the server addresses are prioritized in the same order as they appear in the table. (i.e. The priority ranking [1, 3, 3, 5, 5, 5, 5] should work just as well as [1, 5, 5, 10, 10, 10, 10] so long as you keep the addresses in the right order.)If you’re asked to specify the type of each record you’re adding, enter “MX”.
MX records often require the specific format of DNS records, including a trailing dot (”.”) at the end of any full-qualified domain names (e.g. “server.example.com.”)
Set any TTL values to the maximum allowed.
MX Server address Priority
5. Also you need to create CNAME record for your domain. Delete(If applicable) the existing CNAME entry for the alias or unique string. For example, if you're creating a CNAME record for 'mail,' be sure to delete any existing CNAME records for 'mail.'
Below is the example :-
Host Name/Alias Value/Destination
Custom URL: mail.yourdomain.com. ghs.google.com