At least 2 genuine email addresses are being labelled as "Spam" by Virgin Media. I have not had this issue before having been with VM since the beginning. Previously these email addresses have got through OK.
I have been into the spam folder and indicated that the emails are not spam and they then come through correctly however subsequent emails still go to spam.
you will see that it says "If emails from a particular sender are being identified incorrectly as SPAM, save the sender as a contact. This will ensure that you receive all messages from that sender and their messages won't be identified as SPAM. For more information on how to add a contact, check Using the Address Book in Virgin Media Mail."
However, it is not a complete answer because it depends on why the emails are being flagged as spam.
If the checks that Virgin Media run on all incoming emails suggest that the sender's email address may have been spoofed (falsified) they will continue to flag them as spam.
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This issue of messages going directly to the Spam folder despite Spam handling being turned off was noticed by @SDC awhile back and I do not believe a workaround was ever found. Can you confirm that if you view the message source you see lines similar to the following: