I can only comment on what what I see at my own ISP (Internode Australia), but perhaps Virgin's "spam management option' has a facility which allows you to kill held messages which you "confirm' as spam, and to view and/or release the good ones. At my ISP, this latter action (release) makes them available for your email program to download in the next session, and also adds them to the friends list which means that future messages from that source will come through unimpeded.
You may have to hunt for it, but I would expect that Virgin should have a similar feature.
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