File this along with the advice about resignation letters to state nothing but
"I am writing to give notice of my resignation from <company> on <today's date>. According to the terms of my employment contract my final day will be <leaving date >. -- Sincerely, <name>"
"I am writing to give notice of my resignation from <company> on <today's date>. According to the terms of my employment contract my final day will be <leaving date >. -- Sincerely, <name>"