I had/have the same error, called VM and was told that this is an issue as they are joining all the VM domains (ntl, virginmedia etc) on one server. On asking why I was not informed they said that I should have received a letter, I never did. On asking when it would be resolved, they said 2-3 weeks ! They gave me a back door entry for ntlworld email account: type in the http window, mail.ntlworld.com may work for other VM email addresses.
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