bsmtp(1) on Linux
The text b0c7c542e0ea, as Debian 8 (Jessie) shipped it.
Bareos's SMTP client (mail submission program)
Flags it lists
-
-4 -
-6 -
-8 -
-? -
-a -
-c -
-d -
-dt -
-f -
-h -
-l -
-r -
-s