Actually what's needed is for the old virgin.net mailbox itself to be deleted, obviously it still exists and is accepting email which the rule is forwarding on. The rules are associated with the mailbox itself and will carry on working while the mailbox is still there.
What would have already been deleted or disabled, is the second part of the setup, which is your user account which had access to this mailbox - and this is why you can no longer get to it to make changes but it still seems to be accepting mail. Think of it like a red pillar box where the slot is still open but the door has been welded shut. The box is still there and can accept new mail, there's just no means now of getting to it. Of course, ideally both would be deleted at the same time but for reasons probably related to VM being an amalgam or different companies and systems all merged together over the years with an IT system possibly being held together by the equivalent of some post-it notes and the engineers who understood it have long-since retired or been let-go.
And I only really mention all of this because it has managed to trip a couple of posters up who either don't or won't understand that although the mailbox might still exist and accept mail, the associated user account has gone so there's simply no way to access it.
Anyhow, I'll escalate this thread to the forum staff, one of which will offer to contact you for some details and raise a ticket to have the entire mailbox permanently deleted.
John
