For some time now, I’ve been using Thunderbird Portable to manage my email accounts. For me, it has several advantages over other options:
With all my email from all my accounts gathered in one place on a flash drive (and backed up–usually daily, because the flash drive WILL fail eventually–to a hard drive by simply dragging and dropping the whole Thunderbird Portable folder), I can take it with me wherever I go and still not have to mess with the cumbersome nature of even the best webmail (a tossup between GMail and Yahoo Mail, IMO–Windows Live is for very sick, thought-to-be-extinct Dodo birds *heh*). Simple, and I can still use it whether in a Windows or Linux–or even PCBSD–session (as long as WINE’s installed in the ‘nix box). Really snazzy solution.
But. What about when an older OS or computer refuses to release a flash drive and getting it disconnected causes file corruption (even shutting the computer down may not avert that problem)? That’s a good reason to not only back the mail up every day but to configure T-Bird to leave the messages on the server, not simply delete them on download. Yeh, yeh, that could mean dropping in on some accounts and manually cleaning out clogged up mail folders every now and then, but that’s a very small price to pay.
Besides, with daily backups, it’s doubtful one would lose much mail even were T-Bird not configured to leave mail on the server. One corrupted startup and… simply reinstall over the existing installation, and if mail needed to be copied over from backup, no problem.