The lines of text that form the message
header are saved to the qf file, one per
H line. Any header lines added by
sendmail are also saved to H
lines in the qf file.
The form of the H line is:
The H must begin the line, and the
definition must immediately follow with no
intervening space. The definition is
exactly the same as, and obeys the same rules as, the
H commands in the configuration file (Section 25.1). Beginning with V8.10, if the header lacks
header flags, an empty pair of ? characters are
prefixed to the definition.
When sendmail writes header lines to the
qf file, it preexpands
sendmail macros (replaces expressions such as
$x with their values) and preresolves conditionals
($?, $!, and
$.). Beginning with V8.10, the headers in the
qf file might have been rewritten by rule sets.
The order in which H lines appear in the
qf file is exactly the same as the order in which
they appear in the delivered message.