"Well done letter"?

When I do things like this, I try to keep it relevant to what the job well done was. Since you received an email, I would include as much of that information as possible. Maybe just a few paragraphs:

I believe it's important to recognize when people go above and beyond to accomplish our goals. In working with project X, I know that you've done this, that, and the other thing. Person A wrote the following about your performance in this area:

"Quote relevant email bits here."

Thank you for continually providing our customers and our company with exemplary service.

Personally, I don't do written letters. In our customer service environment, I write an email or use the customer's email/letter itself. Nice foil-bordered certificate paper is not expensive. Nice heavy presentations folders for them are equally inexpensive. I print a Certificate of Appreciation with a small blip about the task they excelled at, and place it in the binder (with a copy of the customer letter behind it so they have that specifically). I keep a copy of the original customer letter in with the reward/recognition section of the employee's binder.

I usually prefer to receive (and send) the actual original email (snipped of whatever needs to be snipped) forwarded with a note. That can be printed and put into a file just as easily as a formal note.

Would the M-T "Thank You" note format work here?

Glad to help, Terri! Let us know how it goes.