What is my username? October 26, 2016 01:46 Follow Your username is the email address that you used when you first sign-up or logged on to Last Letter. Did this answer your question? If not, you can check out the frequently asked questions or send us your question. Read our story, sign-up to get started with your Last Letter or tell your friends and family about Last Letter on Facebook and Twitter. Have more questions? Submit a request 0 Comments Article is closed for comments.