We were faced with this question some time ago, and the result was the
creation of the "IETF Non-WG mailing lists" page,
<https://datatracker.ietf.org/public/nwg_list.cgi>
The theory being that if something is listed there, the IETF definitely
considers it an IETF list; if it is not listed, it's either not an IETF
list, or someone needs to take an action to get it listed (which is simple).
I think defining rules about what is or is not an IETF list is tricky; it's
simpler to list the ones that are.....
I think that is a reasonable approach. Hopefully some of this info is sent in
the welcome to the list mail someone gets when subscribing to the non-WG lists.
John
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