VirginMedia mail insists on putting mail from 38 Degrees in my spam folder.
I have their address in my contacts, and every time I get a message I mark it as NOT Spam.
When Virgin Media announced their email system here is how they described spam filtering:
⋮To help keep your mailbox clutter free, SPAM will be blocked by our state of the art filters. You can change this to deliver it to a SPAM folder or your Inbox instead.⋮
Sadly the reality is anything but state of the art and more than a year on that continues to be the case.
With regard to address book contacts and misidentified spam I can only infer a lack of User Level filters.