Been a Virgin customer for a couple of years now and I must say that since the revamp to virgin media things seem to have deteriorated a little. I am on plan three which does only give 5 mail boxes. Higher priced plans may give you more.
I have been trying for days to configure the mail boxes by signing into 'customer zone' and the 'my mail' link but keep getting a server error message.
If you have been with them for more than 12 months you may want to consider changing, as I am, to Plusnet who have no frills packages from £9.99 a month and a local rate, Sheffield based support center.
If within the 12 months be prepared to pay a £50 get out fee. You will unfortunately also need to request a mac code for the transfer which takes about a week to come through.
Hope this helps.