heirloom-mailx(1) on Linux
The text 84ebce273711, as Debian 8 (Jessie) shipped it.
send and receive Internet mail
Flags it lists
-
-B -
-D -
-E -
-F -
-H -
-I -
-N -
-R -
-V -
-d -
-e -
-f -
-i -
-n -
-t -
-v -
-~