[CentOS] Help with /usr/share/sendmail-cf/m4/proto.m4 - fax macro

OK.  Digging into this...

sendmail.m4 has the lines:

       define(`FAX_MAILER_PATH',`/usr/bin/faxmail')dnl
       define(`FAX_MAILER_ARGS',`faxmail -d -n -p 12pt $u@$h $f')dnl
       MAILER(`fax')dnl

proto.m4 has:

`R$+ < @ $+ .FAX. >     $#fax $@ $2 $: $1               user at host.FAX',
`ifdef(`FAX_RELAY',
`R$*<@$+.FAX.>$*                $: $>MailerToTriple < $F > $1 <@$2.FAX.> 
$3     user at host.FAX',

sendmail.cf has:

R$+ < @ $+ .FAX. >  $#fax $@ $2 $: $1               user at host.FAX

If the To: header is:  joe at 222.fax.foo.com

creates a -d argument of:  >joe<@2201.fax.foo.com.

changing the proto.m4 to:


`R$+ < @ $+ .FAX. >     $#fax $@ $2 $: $1               user at host',
`ifdef(`FAX_RELAY',
`R$*<@$+.FAX.>$*                $: $>MailerToTriple < $F > $1 <@$2> 
$3     user at host',

makes no difference....

So either I need a LOT of help understanding the expressions in proto.m4

or

proto.m4 is NOT the source of the content of sendmail.cf and I need to 
find the REAL source....