H line

H line

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Header line

All versions of sendmail

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:

 H   definition   

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.