Provided by: qmail_1.06-4_i386
preline - prepend lines to message
in .qmailext: | preline command
preline feeds each incoming mail message through command. At the top
of each message it inserts a UUCP-style From_ line, a Return-Path line,
and a Delivered-To line.
preline is useful for procmail and ELM's filter, which do not
understand the qmail-command environment variables.
-d Do not include the Delivered-To line. You should use this option
when the recipient of the incoming mail message is actually
under remote control, but was sent here through
control/virtualdomains for manual routing.
-f Do not include the From_ line. You should use this option except
for commands that create mbox files.
-r Do not include the Return-Path line.