Great for employees who are leaving a company, this letter is addressed to close coworkers.
Dear {Recipient},
I'm reaching the end of my days at {company name}, and I wanted to take a moment to especially thank you and say goodbye.
You have made my time at {company name} all the more interesting, fun and productive. You were there when I needed help on{name of project}, and you always made sure to keep me in mind when it came to{something fun employees did during their downtime}. I felt comfortable at {company name} instantly when {maybe something the coworker did early on to ease the sender into the company}, and I won't forget that.
I am moving on, but we can still keep in touch, and I hope we do. Good luck with all you do in your future at {company name}.
Take care,
{Sender}