Received from J_Catlady at 12/18/2018 09:51 AM UTC:
Currently, members can start an infinite number of topics with the same name. Should this be allowed,
Assuming it isn't allowed, how will it be detected and enforced? It seems to me that enforcement requires looking at all messages with the same subject line and flagging the ones that are off topic. That doesn't seem like something that's even remotely practical to do via programming.
or should messages bearing the same name as an already existing topic be threaded into that topic?
If threading is done by Subject:, that's about the only option.
Some email clients can thread based on "Message-Id:" and "References:" headers, but I don't know of any web based email lists (like Groups.io, Yahoo Groups, etc) that do that.