When it is the last day in any organization, people generally write e-mails to inform everyone about it and also to give them a vote of thanks. This e-mail is generally short consisting of 2-3 short paragraphs. At the end, give your personal ID if you want to stay in touch with your past colleagues.
Today is my last day in ABC (name of the organization). It was a great journey for me at ABC from September 2006 till today (customize the tenure). I was lucky to participate and contribute in the Transformational change that ABC is going through and more importantly, to work with "get in and get it happening people" around me.
I am indebted to my mentors in this journey who guided me and helped me shape up my career. Many thanks for providing me support and encouragement all the way…
I can be reached on e-mail at (provide your personal e-mail ID). Wishing you all “good luck” and great life ahead!
(Write your name)