>>I'm disqualified, because I'd suggest to use Thunderbird. Ignore this message.
>
>I can't ignore it. Would Thunderbird work in Windows 7?

I used it under W7 for several years, without a hitch. I actually have an unbroken set of emails from 1998 to now, initially maintained in Netscape, when it was both a browser and email client. Then under Mozilla they split responsibilities. But the file format didn't change - it's still raw text as received. The files can grow above 2G, but there's the archive option (which in my case isn't enough, there's a work related folder where I now split a year into multiple archives).

Migrating it to Linux then was a matter of writing one path into a profile.ini file, as would the migration in the other direction. There's actually still a few missing fonts, but it manages without.