Depends how they do it. If ntl map the old addresses over to the new ones, that is more complicated for them. But for us, makes no difference. They would probably run the ntlworld and virgin addresses in paralell with each for six months to give everyone a chance to switch over to the virgin ones. Ie if someone sends you a email to
joebloggs@ntlworld.com that would instantly map over to
joebloggs@virginmedia.com.
Or, they may just do what ntl did when it took over Cable & Wireless (CWC). We all had to sign up for a new ntlworld email address as the CWC addresses were from then old managed by Boltblue, a totally seperate ISP. Eventually, the CWC addresses got changed to bolt blue.
Can't say I really keen on having a "virgin" email address though. I would have thought that the email might be @virgin.net as that exists already rather than creating a new virginmedia one. That would probably be used for staff only.
What we can be 100% certain of, is that at some point the ntlworld name will disappear completely. Ntl's bosses have made it clear that once they become "virgins" they never want to see or hear the name ntl again. I'm sure we can remind them, though