For years I used Microsoft Outlook before I moved to Thunderbird to manage my email. The big drawback was that I needed to be at my computer to refer to old mail and searching through it was at best difficult and slow.
For the past year I have been using Google Apps which includes their excellent web mail application. By migrating my old mail 'into the cloud' I now have a fully searchable repository of my past twenty years email, accessible from anywhere in the world where I can find an Internet connection. This is a huge step forward. The spam handing is as good as I have seen - there just isn't any - and you can even work on your email when not connected to the Internet, how good is that?
Moreover I still have my own domain name (email address) and no longer need to run my own email server. I suspect the power saving alone is worth the $US25 per annum that the service costs for the full version. You can use it for nothing if you prefer. Give this service 5 stars.