From G.P. Imports:
With Email Groups Pro for iPhone get distribution list creator for all providers. It Works for all your contacts listed in your address book. Email Groups Pro for iPhone application lets your create groups of email contacts so you do not have to select every single recipient every time you want to send an email to multiple recipients. It features multi image attachments, easy to locate groups, no need to add contacts one by one, you can add one specific contact to multiple groups unlike similar apps, you can add, delete all groups, and works with the native address-book application.