Although the high-visibility player remains the Web and browsers to access and view it, experienced Internauts agree that the most important application in terms of day-to-day value is electronic mail. E-mail is the most pervasive of all Internet activities and the most flexible.

I'd argue that choice of E-mail client software is more important than browser selection because your E-mail program is responsible for information created or sent to you, material you can't simply go back out to the Web and re-retrieve. So don't casually default to some mail program because it's bundled with your Web browser.

Compared to the browser market, there are fewer players here, but slightly more major players. The big names in mail clients are Agent, from Forte (note that Agent is also a Usenet client); Eudora, from QualComm (try the full commercial versions as well as the shareware one); NCD's Zmail; and Pegasus. Other players include Uqwk, Emacs (in its E-mail mode), Pine and the venerable Unix "mail" program. Lotus Notes also does E-mail, although I'm not impressed by how well. Most players have Windows, Mac and Unix versions.

Full suite vendors like Hummingbird (they bought Beame Whiteside), FTP Software, Netmanage, PSI/InterCon, TGV, Wollongong, etc. include a mail client. There are also mail programs for desktop and LAN environments: Microsoft's Exchange, Novell MHS, Lotus cc:Mail ... and assorted other general-purpose mail clients. (Unix and other workstation operating systems include mail clients.)

In terms of reliable, effective E-mail, the critical portions will be what you choose for "mail backbone" products-the backend message store and post office servers. You'll also need to worry about nontrivial issues like address resolution, directory syncronization transport and addressing protocols, and content handling/conversion. If you're not primarily a TCP/IP-oriented facility, and enterprise E-mail is important, give this part of your network the attention it deserves to be done right.

Depending on how your company uses E-mail--and how much E-mail people get or send-features to care about include:

* MIME (Multipart Internet Mail Extensions) handling and viewing of attachments;

* Offline mail (i.e., reading and creation messages when the user's computer isn't connected to the mail server);

* IMAP (Interactive Mail Application Protocol), which allows a user to selectively specify which messages--and even which attachments--they want brought to their disk, and which ones the mail server should hang onto. The client and server must both support IMAP; Sun recently introduced new IMAP client and server programs.

Here are some good Internet resources for discussion and product/vendor evaluations of E-mail (and, in some cases, downloadable software): Various comp.mail.* Newsgroups (try comp.mail.misc) for Q&A, discussions, bug reports and some announcement; you may also want to watch comp.archives.

On the Web, required bookmarks for Windows users include Forrest Stroud's Consummate WinSock Apps Web site (http://www.cw sapps.com) and TUCOWS (The Ultimate Collection of WinSsock Software, hhtp:www.tucows.com).

Some closing thoughts: Be sure to scan E-mail attachments for viruses (including "macro viruses"). Pay attention to security considerations of mail programs, and of mail connectivity to the Internet.

Danieldern (ddern@world.std.com, http://www.dern.com), Internet analyst, author, columnist and speaker (and ask me about the Internet Paper Airplane), can be reached at 617-969-7947. His snailmail address is P.O. Box 309, Newton Centre, MA 02159.