When a header screening rule set is defined using the
H configuration command's
* in place of the header's name:
H*: $>CheckBanned
the header that caused the CheckBanned rule set to
be called is not passed in the CheckBanned rule
set's workspace. To make design of such rules
possible, sendmail offers this
${hdr_name} macro. It contains as its value the
current name of the header being processed. The name is stored
without a colon. One example of a use for this macro can be seen in
Section 25.5.2.
${hdr_name} is transient. If it is defined in the
configuration file or in the command line, that definition can be
ignored by sendmail. Note that a
$& prefix is necessary when you reference this
macro in rules (that is, use $&{hdr_name}, not
${hdr_name}).
