My last day of work here will be ____________ (date). This will give me three full weeks from next Monday to complete the current marketing programme design that I have recent been putting the finishing touches on.
In addition, during this period I will be able to bring you, and my deputy (name of that fellow), up-to-speed on all of the operations and outstanding issues in my department.
I am very much looking forward to the professional challenge being offered to me by (Company Name), which as you know, is the market leader in its field. Incidentally, during the recruiting process, the Global Solution people were very impressed with the experience and knowledge that I had gained here over the past five years.
In closing, I would like to express my sincere appreciation to you as my supervisor, as well as to my many friends and colleagues here. I have truly enjoyed my years working with all of you, and am grateful for the many learning and growth opportunities I was given over the years.
I wish all of you working here a continued success.