The bulletin directory contains one file per bulletin. Each file contains a single mail message with header and body in mailbox format. The easiest way for sysadmins to create such bulletins is to mail themselves a copy of the bulletin using the account to which they want replies to be sent, then use their mail program to save the message to a file in the bul- letin directory in mailbox format. The bulletin directory must be world readable. The name of each bulletin file begins with the bulletin number, and may optionally continue with any other charac- ters.
Popper creates a file named .popbull in the home directory of each user.
This file contains a single line recording the highest numbered bulletin received by the user. Each time a POP client connects to the server, any new bul- letins which the user has not received previously are automatically appended to the user's mail. Otherwise, the bulletin is copied as is. When a new user checks for mail the first time, popper creates the .popbull file in the user's home directory and seeds it with the current maximum bulletin number. Thus new users do not get old bulletins.