I wonder if anyone here has tried the mail program qpop: http://ultrapop.jp/?qpop ?

I couldn't find any mention of it here (or indeed anywhere else on the English-speaking web). I have just installed it on my new 3100 and it seems to work although my Japanese isn't very good so I haven't sorted out all the settings. But it looks pretty good, with things like real filters. It's still version 0.X so may be rather incomplete...