Messenger Express supports the most popular browsers such as Netscape Communicator 4.x, Netscape Navigator 4.x and 3.x, and Microsoft Internet Explorer 4.x and 3.x. Messenger Express is resident on Enterprise Server and so does not take up system resources on the desktop. In other words, no additional desktop software is needed. Messenger Express provides basic email functionality such as sending and receiving email and managing messages and mail folders. It is designed to be the secondary email client for quick email access from any computer with a browser.
Communicator is designed to be the primary email client for most corporate users.
Messenger Express provides a quick way to deploy such a client so roaming users can access their email from any computer inside the company or outside the firewall if configured appropriately. Messenger Express supports the goal of a totally thin, second email client for quick email access better than Microsoft Outlook Express does because Messenger Express doesn't take up system resources on a user's hard disk when not in use. It also works on any platform supported by the major browsers. Outlook Express, on the other hand, is another full client that takes up system resources, such as the user's hard disk, even when not in use. Messenger Express runs on any platform that Communicator 4.x, Navigator 4.x and 3.x, and Internet Explorer 4.x and 3.x support.