The 'Mailbox unavailable message usually means that your email account has been locked for security reasons.
The Forum Team (VM employees) will be able to unlock the account for you. Be patient and they will contact you via this forum and get things sorted.
******************************* I am just another Virgin Media customer. If someone posts a useful reply you can say thanks by clicking on the thumbs up sign in their post. If someone posts a message that solves your problem it helps everyone if you mark their post as a Helpful Answer
Welcome to our Forums and thanks for your first post - I am sorry to understand that you're having some issues with your emails at the moment.
May we ask, do you still have an active Virgin Media account that the email address is linked to?
If so then great, we can look into what seems to be the issue for you; can you advise how you are trying to access your emails? Is this via webmail or via an email client? Are you still able to log into your MyVirginMedia account ok?
If you no longer have any active services with us then I am sorry but we would not be able to help you any further; when you leave us, your email address should be removed within around 90 days or so. You can only have email services if you are still a customer with us.