I am interested in the same thing. You have not had a reply in three months, so I would guess there is little or no interest in the subject. I too, have a client who likes listserv, and just opening a new window for Google Groups is all I can do. Maybe someone else can help, here.
You would think that either a moderator or product manager would answer you post.
This currently isn’t possible.
Such a feature has been mentioned before and is on a list of requested features, so hopefully something will materialize in the next few months.
Any updates on this? A feature like this would be ideal for my development site.
if I recall well, @r-a-y is on top of this one – for BP 1.5 – 1.6 – 1.7
@mercime – *whispers* ssh! it’s a secret!
That’s all I can say for now!
@r-a-y – *whispers* ok. best wishes 
hum… do you know how to follow @r-a-y about this plugin? is he working on this already?
thank you all
+1 for this… any way for us keen peeps to be the first to know?