smtp-source(1) on macOS
The text 2d53ed71eb7e, as Mac OS X 10.6.8, Mac OS X 10.6.7, Mac OS X 10.6.6, Mac OS X 10.6.5, Mac OS X 10.6.4, Mac OS X 10.6.3, Mac OS X 10.6.2, Mac OS X 10.6.1, Mac OS X 10.6 shipped it.
multi-threaded SMTP/LMTP test generator
Flags it lists
-
-4 -
-6 -
-A -
-C -
-F -
-L -
-M -
-N -
-R -
-S -
-c -
-d -
-f -
-l -
-m -
-o -
-r -
-s -
-t -
-v -
-w