They are swapping over to Google mail (I think). I'm with Virgin and mine changed yesterday, but the only glitch I had was on my Outlook at home I suddenly received hundreds of previously deleted emails from their server. no major issue, just a pain to sit and delete them all again. My Outlook and webmail have been behaving themselves without issue (So far) since the switch, and I must say it's a massive improvement from the old Virgin webmail, much quicker and smoother, and more features.
Hope everyone else gets sorted as quick, maybe different people are being switched over on different days.