dear mr. smith,
i am sorry to inform you by this letter that i plan to resign my present job in the next month. the main reason is that i will move to qingdao to live permanently with my family, as qingdao is my hometown.
looking back upon my five-year experience in this organization, i have had a very happy and enjoyable time working with you and other colleagues, from whom i have received lots of help and have learnt much. please accept my sincere gratitude, as well as my regret for not being able to serve here any longer.
yours faithfully,
li ming