The late 1990s saw a new type of email service, coupled with a new economic model for such services: Web-based email. These mostly free services are generally supported by advertising revenue and so incorporate advertisements into the user interface. A combination of HTML frames, tables and client-side JavaScript is used to present a modern, if clearly Web-oriented interface. They are, as stated earlier, properly MUAs. They connect to standard MTAs and MRAs in order to send and display messages. MUA functions are simply distributed across multiple machines; read and write functions are on the server while the user interface is interpreted and executed within a Web browser.

Since most new Internet protocols in the standards track are being defined with a URL access syntax, this model could become the basis for a new face on network services. The Web browser, designed to be a nearly universal interface, is a perfect single application for small network appliances. Cellular telephones, PDAs, and palmtops would surely benefit from such a model when connected to the network.

The development of this model has slowed since the end of the Microsoft-Netscape browser war, but one should probably view it as a hiatus in the conflict rather than a true browser peace.

Web-based email has already become a favorite for traveling executives and salespeople for use while on the road. As useful as it is, more needs to be done to integrate these services into a corporate lifestyle.

For example, consider this common scenario. A traveling salesperson has a desk at his home office. While there, he uses a desktop MUA that is integrated with other corporate applications. While traveling, he uses Web-based mail. Unfortunately, this means that he has to maintain two separate sets of mail folders. There is no easy way to transfer messages from one place to the other, short of remailing and hence refiling them. Messages may be sent to only one, or both, accounts. If he used Web-based mail from the home office, thereby using only one account, he would not only lose integration with office applications, but might also have a slower connection to the mail server. This is clearly not an optimal solution but is not unknown among travelers.

Now consider a better scenario. The corporation in question decides to offer its own Web-based mail service for employees. Using standard protocols and mailbox formats, the user’s desktop MUA can read and write the same mail folders as the Web-based service. The Web-based service is protected from intruders through the use of strong authentication such as digital certificates. The transmission may also be encrypted, protecting sensitive material from the public view. While at home, the user gets a full featured MUA. While on the road, he can access his mail from any Web browser, be it on a laptop or at an Internet cafe.

This scenario also has other advantages. If the salesperson wishes to work offline, he may use a laptop MUA that locally caches both received and outgoing mail. The advertising inherent in the free services is also avoided. In any event, it is a very flexible alternative that was made possible solely by the use of standards. One wonders who will first create a Web browser with which it is possible to use such applications offline.