J,
Every member of every Grouos.io group knows by the 'M' badge in their
groups list if they're on moderated status.
Correct.
They do not know who *else* is on moderated status. Including the info
in the headers would reveal that to them.
Sort of.
Joseph's method (looking for a delay) will work just as well on someone else's message as on on your own if you have it in individual mail and can examine the Received: header fields.
A member can't use View Source on the web to do that (alas, or thank goodness, depending on your point of view).
Shal
Shal Farley