You have a choice in webmail programs. You can pick whichever one you are most familiar with, or the one you learn to like over time. You can switch webmail programs as much as you like, and you will still see all your emails.
Horde is a feature-rich, customizable, versatile, and extensible web-based e-mail client. USers can customize their own folders, calendar, address book, and welcome screen, to name a few features. Horde users may also customize every aspect of the webmail's display including colors, arrangement, and welcome screen (importing weather, news feeds, external websites, and any other external plugins desired). Many Universities and other professional establishments employ Horde webmail to meet their email needs.
SquirrelMail is an interface to your organization's email system through the web. It has all the functionality you would want from an email client, including strong support for attachments, address books, calendar and folders. Also, SquirrelMail is highly customizable and has low amounts of graphics, which means faster page loads.
RoundCube is a browser-based multilingual IMAP client with an application-like user interface. It provides full functionality you expect from an e-mail client, including MIME support, address book, folder manipulation, message searching and spell checking.
Don't forget, you can change webmail programs
anytime, and you will still see the same emails.