A popular function of bulletin boards like vBulletin and phpbb. It allows registered members of a forum to send private messages to each other. To works somewhat like email, except it's limited to only a select number of registered members of one specific installed bulletin board. You cannot send a private message to someone registered on another installation of the same bulletin board. A private message will usually allow you to include vB Code, smilies and images unless it's denied by the admin of the board. Sending a message is a simple process, you right click any member and then select 'Send A Private Message', fill in the blanks and then press send. Your private mail folder is usually divided into sent items, unread messages and read messages. There is usually a maximum folder storage space limit enforced.