Dear All,
I want to take a moment to let you know that I am leaving [your future ex-company] after # year!
I will be starting with my new job next month.
I have enjoyed my tenure here and I really appreciate the opportunity to work with you. Thank you for the support, guidance, and encouragement you have provided me during my time at [your future ex-company].
Even though I will miss my colleagues and the company, I am looking forward to this new challenge and to starting a new phase of my career.
Thanks again for everything.
[your name]
[your contact details]
