I have a fairly standard approach to using ISPs for e-mail, and that's just don't do it!
Sorry, know you are hinting at the idea you are switching ISP, but my bold comment above was really for those who aren't switching...
I have been recommending people use independent services (whether free or paid) such as GMail, Hotmail / Live.co.uk / Runbox.com / FastMail.net rather than the "ISP Mail" partly because you then have the ability to switch ISP without worrying about losing contacts from the address book, and partly because the mail services are very, very, good, while many ISPs seem to struggle to keep their mail service going (or are overloading them, by the time they have a few million customers like the "big ones" {BT, TalkTalk, Sky, VirginMedia, Orange/EE } )
For someone self-employed, or running a business, getting their own domain name generally looks more professional, too, and you can have just e-mail without a web site (though a basic site, with contact details might be worthwhile).
Good luck with switching!