postlock(1) on macOS
The text 58d347aeaa1a, as Mac OS X 10.3.9, Mac OS X 10.3.8, Mac OS X 10.3.7, Mac OS X 10.3.6, Mac OS X 10.3.5, Mac OS X 10.3.4, Mac OS X 10.3.3, Mac OS X 10.3.2, Mac OS X 10.3.1, Mac OS X 10.3 shipped it.
lock mail folder and execute command
Flags it lists
-
-c -
-l -
-v