This file extension represents an actual new mail message. When new mail arrives for a user, it will have this suffix (this is compatible with direct server delivery, Mercury and Charon). The filename is unique, and can be considered as its message id. The actual name generally begins with a Y to indicate a normally delivered new mail message (local or by Mercury), or P to indicate a POP3-delivered message. If the general preference to keep new messages in the new-mail folder is set, in the versions before the 3.0, the first character of the message id will become a ! when the message is read but not moved. In the 3.0 version the file is no longer renamed. The structure of the New Mail folder is unique in that individual messages are stored as individual files whereas other folders have all their messages stored in a .PMM file with a corresponding index file with a .PMI extension - one file pair for each folder.
File extension used by NoteMap.