Question (not defending Sky as this applies to any ISP): If email is so important, why leave it to your ISP to provide it?
Google's mail service (gmail) is very good (although I have privacy concerns so no really personal stuff) and it's free, accessable anywhere and offers great spam/virus filtering.
For total control, buy your own domain name and a bit of cheap hosting - about £10/15 a year - and you have complete control over all your mail that is independent of any service provider. You can change your isp daily and keep the domain name.