In order to use the complete set of features, and get the best possible experience from CatMail, you need to use one of the recommended web browsers:
Other web browsers will work for accessing CatMail, but you'll see a "light" version of the interface, with a different appearance and not all features available.
If your web browser isn't listed above, consider downloading and using one of the following:
For more information on exactly what features are available in which browser, see also Microsoft's list of Supported Browsers and Operating Systems.