If you prefer using a mail client on your local computer as opposed to accessing your email via a web interface and are looking for a portable solution, you might want to take a look at i.Scribe.

Scribe is a small and fast email client with an intergrated contact database and calendar. It supports all the major internet mail protocols and uses international standards where possible. Scribe doesn’t required installing or uninstalled and can be used from a removable drive without reconfiguration. It comes with a bayesian spam filter and translations to many different languages. Updates are published regularly to respond to problems and to add features. Because Scribe runs on Windows and Linux you can take your mail with you when you change operating system.

Note the big feature here: portability. You can copy i.Scribe to a flash drive and take the program with you and run it from any Windows or Linux machine with access to all your mail, calendar, contacts and account settings.

There are lots of other features available as well such as the bayesian (i.e. learning) spam filter which make this a really great alternative. You get all the power of a desktop application with all the portability of web mail which makes this an awesome combination.