Where do you want to put canned responses?

Try using the Clippings add-on.
https://addons.mozilla.org/en-US/firefox/addon/clippings/

In my replys. I am expecting numerous emails in my inbox to register for a stress seminar I am conducting. I would like to response to each with a response; something like, Thank you for registering for the Stress Beyond Coping Seminar. I look forward to meeting you there.

I followed your link and downloaded clippings add-on. I restarted firefox thinking I might see where to start using clippings. I haven't found it yet. What next?

Did you read About this Add-on?

Also, there's a quick start guide here:
http://clippings.mozdev.org/quickstart.html

OK I got it. Thanks problem solved