You will have to create your groups using the Contacts app. If it's a Gmail account, you can do it from your computer as well.
Open the stock Email app.
Create a new message.
The cursor should now be in the To: field
Press the menu button.
Select Add CC/Bcc
Place the cursor in the Bcc: field
Start typing the name of your group.
When you see it appear in the drop down menu, select it.
It will then load all of your contacts in that group with an Email address.
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