Dear …
I have accepted an offer with another firm and ask you to accept this as my formal notice of resignation with __ (name of company)__. The last day of my employment will be __ (date) __.
My time with __(name of company) __ has been very rewarding and beneficial to my career and I hope that my contributions to the company have been equally as valuable. I have accepted a new position that will expose me to challenges and opportunities which I believe are in the best interest of enhancing my career.
You and the company have been more than fair with me, and I genuinely appreciate all your support. I wish __(name of company)__ continued success, and I want to thank you for allowing me to be a part of your team.
Sincerely,