Let's be clear here. There are TWO ways that this can happen. Firstly, as has been suggested, someone could have hacked into your email account to send spam to lots of random addresses. However that's actually quite unlikely since Virgin's email service would normally reject such bulk mailings in order to prevent spam being sent through their servers.
Secondly, and (in my opinion) far more likely, a spammer has sent mail from somewhere completely different to your email account but with your address entered into the 'from' and 'return' fields. They could either have got your address from hacking the website of a firm that you buy stuff from (or of a forum that you contribute to, like this one) or, far more likely, by simply guessing at it. Their computer is set to send mail to
[email protected],
[email protected],
[email protected],
[email protected] and to millions of other addresses that
might actually exist. It's just as likely that they'll enter a random address (which just happens to be yours) into the 'from' and 'return' fields.
You probably need to do nothing at all, since the spammers constantly change the addresses they use in the 'sent' and 'return' fields. However, just to be on the safe side, it might be best to change your password. You should also take care to check, over the next few weeks, that your genuine email recipients are actually getting the mail you've sent to them. (It's possible that some servers might block mail from your address because it's been associated with spam). You should also consider whether you should continue to use a 'guessable' email address (if you actually do so, of course). An address such as '
[email protected]' is a lot less easy to guess at than '
[email protected].
Chris