Threading based on Subject

[Richard Lewis <richardlewis@fastmail.co.uk>]

Hi there,

I seem to recall that Wanderlust allows the customisation of threading
of messages based on their having matching Subject lines.

One of our customers uses an issue tracker which sends sends lots of
emails without proper References or In-Reply-To headers and being
able to group these messages into threads based on Subject would be
very useful. However, Wanderlust is not doing this for me at the
moment. Is it something I can configure?

Thanks,
Richard