sendmail problem in expanding macros in headers

[matt at oddjob.UUCP]

Why won't the sending hostname from the SMTP HELO command
appear in the "Received:" header?  Running with debugging
shows that macro 's' is defined correctly upon receipt of
HELO.  Starting sendmail with a flag "-oMsfakehost" gets
" from fakehost" into the header, but a $s from HELO gets
lost somewhere.

The header is defined as:

HReceived: by $j$?s from $s$.$?r with $r$.
	id $i; ($v/$Z) $b
_____________________________________________________
Matt		University	crawford at anl-mcs.arpa
Crawford	of Chicago	ihnp4!oddjob!matt

	"Thank you for your support"