Thanks for your reply. Yes, it’s definitely been hacked. The inbox showed lots of messages using an account with .ru suffix, and people who were on my address list were sent spoof email with attachments.
I’ve changed the password and emptied the inbox, also deleted all names from address book. However, the account is still trying to send out emails.
I can’t seem to get any help from Virgin Media - might just have to cancel my package to get the email account deleted!