Files with the PMS extension are used by a program called Pegasus Mail. It is a free email client. It allows you to receive and send correspondence without the need to log into your e-mail account via the website. It is a free solution for Windows family, written by David Harris.

PMS is a file used to store signatures defined in Pegasus Mail by the user. This allows you to automatically add an appropriate signature to outgoing letters, without having to enter it each time.