## for each HEADER in the LIST which appears in the current message, where
## VALUE is the HEADER's current value.
m4_define(<:RENAME_HEADERS_ADD:>, <:m4_dnl
-CLRSEP<::>FOREACH(<:\
+FOREACH(<:\
${if def:h_$:><:1:{X-CONF_header_token-Renamed-$:><:1: $h_$:><:1:\n}}:>,
<:$1:>):>)