mhdr(1) on Linux
The text 1aa0ee58ca8b, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye) shipped it. The page shows this text now.
print message headers
Flags it lists
-
-A -
-D -
-H -
-M -
-d -
-h -
-p