What is a Canned Responses?
Canned Responses is a Lab that allows you to insert pre-formatted content you create into your messages. To enable Canned Responses, click on the gear in the upper right of the Google Mail window, select Mail Settings, and click on the Labs link.
How to Make Canned Responses
To create canned responses, make sure that the canned responses labs in your GMail setting is enable. For more of how it’s done, please watch this video.