Discussion forums and mailing lists are different media; it's like comparing films to TV series.
Anyway, the
forum's focus are specific quotations, with each Christie book receiving a dedicated webpage for quotations from that book, and a dedicated forum thread to discuss those quotations, if there's any interest. There's already been some specific discussion of
Agatha Christie's potentially
“racist” remark in Death in the Clouds. Other differences are that in a
forum, many Christie works may be discussed simultaneously, whereas in a
mailing list set up like this one, the discussion is linear (one book at a time); and there are forum categories for
other writers beside Christie (such as
this writer's forum).
To sum up, both media (
mailing list <->
forum) have their own advantages and disadvantages and they can't really be seen as competing against each other. It would be meaningless trying to set up another Agatha Christie-focused
mailing list such as this one, as it would merely replicate what already exists. A discussion forum such as
christie-forum.aboq.org may add something new and useful.