comsat is the server process which listens for reports of incoming mail and notifies users who have requested to be told when mail arrives. It is invoked as needed by inetd(1M), and times out if inactive for a few minutes.
comsat listens on a datagram port associated with the biff service specification (see services(4)) for one line messages of the form
If the user specified is logged in to the system and the associated terminal has the owner execute bit turned on (by a biff y), the offset is used as a seek offset into the appropriate mailbox file, and the first 7 lines or 560 characters of the message are printed on the user's terminal. Lines which appear to be part of the message header other than the From, To, Date, or Subject lines are not printed when displaying the message.
See attributes(5) for descriptions of the following attributes:
|ATTRIBUTE TYPE||ATTRIBUTE VALUE|
The message header filtering is prone to error.