e off-line, you can browse select messages for downloading into your local cache. If a message has attachments, you can download only the text, or select individual attachments, or download everything. That's real power and convenience.
For this report, we evaluated four mail servers that support IMAP4, the latest full standard. We tested three running under
Windows NT and one under Unix. The NT servers are AltaVista Mail Server 97 version 2.0B, Netscape Mail Server version 2.02, and Fujitsu Software's TeamWare Mail version 5.1 beta. The Unix server is SunSoft's Solstice Internet Mail Server 2.0. (Most of these servers are not restricted to the platforms we tested on.) We concentrated on features, ease of learning, and ease of
administration
. We didn't test specifically for performance because that, along with scalability, is more a function of the overall network than of the server software.
How Do I Access Thee?
For most users, an e-mail program's abilities to store, retrieve, and manipulate e-mail are what matter most. The most widely used protocol, POP, is supported by the mail clients bundled with Netscape Navigator and Microsoft Internet Explorer, as well as by Eudora. IMAP, an alternative to POP, has features and extensions that make it more robust and ultimately much more convenient in client/server computing
environments where multiple clients need to access the same mailbox.
While all four tested products support the latest version of POP (POP3), and all qualify as compliant with IMAP4, they differ in what features and extensions they support (
see the table
for details). Three main functional areas make IMAP a better choice than POP:
1. IMAP offers
better remote access.
2. IMAP supports
folder hierarchies and folder sharing, while POP does not.
3. IMAP allows
searching and selection of messages and message parts, and searching is done on the server, not on the client.
Until recently, the primary reason not to use IMAP was the abundance of POP mail client software, which is included in the two most popular Web browsers. However, Netscape Communicator will have an IMAP-capable mail client, and Microsoft Internet Explorer will surely follow suit.
Most of the differences between IMAP and POP are in how they allow
access to e-mail messages. There are three typical access methods: off-line, on-line, and disconnected. The most common mode on the Internet today is the off-line paradigm ("off" referring to "off the server"), where messages are retrieved by the mail client and deleted from the server. The mail client may be on-line in that it's connected to the Net, but in fact it "connects" only with the mail server long enough to download a new message. The user performs all message access and manipulation on the client, not on the server.
The on-line model reverses this. Messages remain on the server, and the client software manipulates them remotely.
Disconnected access is essentially a hybrid of the first two. The original message files remain on the server and can be manipulated remotely. In addition, copies are cached on the client, where they can also be manipulated. Once the user reconnects to the server, the message files are synchronized to make sure that both machines have the most current version of
each message.
POP is a store-and-forward protocol that was never designed to employ a client/server computing environment very effectively; it fully supports only the off-line access model. POP does have a pseudo-on-line mode in which mail messages can be left on the server, but this mode lacks fundamental manipulation features. Even so, the off-line method works fine for users who always retrieve their mail from the same client computer. But if the user typically checks mail from more than one computer, their messages can become dispersed among several client computers. This makes it hard to keep all the mailboxes up to date because the user has to copy messages manually from one computer to another.
IMAP supports all three types of access, so it's better suited for nomadic mail users, such as sales representatives who may have a desktop computer at the office and a laptop on the road. With IMAP the user's mailbox is central to the server. Regardless of location, they will always be accessing t
he most current version of the mailbox. And they won't have to log unnecessary connect time because any off-line deleting or marking of messages they do will be synchronized at the next server log-in. All the servers in this report support all three types of message access, but not all IMAP clients support disconnected operation.
AltaVista Mail Server 97 2.0B
AltaVista Mail Server's most impressive assets are its administrative interface and its price. The program offers three administrative interface choices: a menu for accomplishing routine tasks like creating new user mailboxes, an Explorer-style interface for getting a bird's-eye view of the mail server's organization and for monitoring its access, and a Web browser interface for remote administration. For a $495 license fee, 250 clients can access the server. (AltaVista Software does not produce an IMAP client, so you would need to supply your own.) As with all three NT products we tested here, a single snag in an otherwise smoot
h installation process took hours of troubleshooting and a long phone conversation with technical support to resolve.
AltaVista Mail Server's security and IMAP server features are not quite as complete as the other two NT programs, despite the fact that this is the only server to currently support IMAP4 revision 1. It seems clear, though, that AltaVista was willing to sacrifice some bells and whistles to make the program easier to learn.
A case in point: AltaVista Mail Server 97 lacks an adequate means of importing user mailboxes. It does offer a protocol for accomplishing the task, but it is not as easy to use as the other programs' import capabilities. AltaVista Mail Server 97 also does not allow automated replies.
The program uses a very smooth setup wizard and runs a server diagnostic utility at the end of the installation. But when we ran the setup, the diagnostic testing results scrolled by so quickly that we didn't see a warning that the server's Domain Naming System (DNS) MX records
weren't found. When our testers started to use the mail server, the lack of the MX records caused mail messages to loop and eventually end up in the dead-letter mailbox. While users of AltaVista Mail Server 97 who employ a dial-up connection to an Internet service provider should never have the problem with MX records, it's still important; about 10 percent of the questions in the AltaVista Mail Server 97 tech support forum deal with looping messages and missing MX records. The other programs didn't balk at the lack of MX records and seemed to use another method to supply the missing DNS information to the mail server.
Netscape Mail Server 2.02
In addition to solidly supporting standard IMAP features, Netscape Mail Server offers the best printed documentation of the group. Its most unique features are its ability to allow users to administer their mailboxes via e-mail forms and its choice of three automatic-reply modes: vacation, echo, and reply.
The $995 price gets you a licen
se for up to 100 clients per server. Client software and licenses for Netscape Messenger should be shipping by press time with Netscape Communicator (the new upgrade to Netscape Navigator) for about $50 per client. Netscape Mail Server currently supports only Finger as a directory-access protocol, but the next version of the program, which will change its name to Netscape Messaging Server 3.0, will add Lightweight Directory Access Protocol (LDAP) directory services.
Netscape Mail Server offers the greatest number of service log files, but it lacks the server diagnostic utilities found in the other programs. The sole means of GUI-based administration is via a Web browser (the others also offer administration software for Windows).
After we installed Netscape Mail Server, the administrative program wouldn't run. After a long conversation with tech support, we finally figured out that our browser software failed because it was configured to access a proxy server. Troubleshooting this problem was diff
icult, for neither the software nor the documentation hinted at plausible causes of the error message. This particular problem stopped testing dead with Netscape Mail Server because the only way to administer the program initially is to use a Web browser. The other programs supply Windows-based administrative clients.
Solstice Internet Mail Server 2.0.
We tested two versions of SunSoft's Solstice Internet Mail Server: one on a Ross Technology SparcPlug workstation running Solaris 2.5.1, the other on a Dell Pentium-based PC. Installation isn't difficult and usually takes only a few minutes (less than 5, in our case), but in true Unix fashion it's all command-line-driven and not very graphical. Inserting the CD triggers the automounter; the disc's contents appear beneath the /cdrom directory. Then you can use the
kgadd
command to load the mail server's components onto your hard drive.
The post-installation script adds IMAP4 and POP3 server entries to your Unix host's inet
d.conf and services files. The inetd daemon will spawn IMAP4 and POP3 server processes when client requests come in. After that, there's still one more step before it will run: You need to call Sun for a software license. The IMAP4 server won't operate unless it finds a license key. This can be frustrating, especially for administrators accustomed to Microsoft's wide-open licensing. But the call doesn't take long, and when it's done you get an e-mail message containing your license key. Copy the key file to the specified location and the IMAP4 server is ready to process requests. In use, we found that administration was rarely necessary except to occasionally clear a jammed lock file. Sun provides on-line documentation in PostScript and Adobe Acrobat formats.
Solstice includes Solaris (x86 and SPARC) and Windows IMAP4 clients, called "roam" clients. These clients have somewhat clunky user interfaces, but they fully exploit IMAP4. Users can access public mailboxes, create new mailboxes, and copy messages
between mailboxes by dragging and dropping. The roam clients are quite smart about managing off-line sessions, queuing user actions until the next connection to the server. Roam identifies and decodes multiple MIME attachments per message.
Users accustomed to more attractive-looking e-mail clients may feel demoted if you tell them they now have to use roam clients. It might be wise to investigate other IMAP4 clients before investing in Solstice Internet Mail Server.
TeamWare Mail 5.1 (beta)
We
tested TeamWare Mail
, scheduled for a March release, in beta form. Installation was more difficult because it requires a separate operation for the administrative software, a step not necessary with the other servers. Even so, the program's large feature set makes it somewhat easier to use once you've learned it. And features like mailbox and message quotas, mail database backup and restore, and LDAP services make the program easier to maintain from an administrative
point of view. TeamWare Mail is the only server we tested that currently supports LDAP. Client e-mail software comes bundled with the server.
TeamWare Mail's GUI isn't as clean as AltaVista's, but it's the only program that lets the administrator limit mailbox size and message size. The program comes with its own backup and restore programs, which can be useful when users relocate mailboxes to a central server.
Groupware and Beyond
Each of these mail servers is just one module in a list of servers that are part of each vendor's groupware line. Add-on modules for bulletin board-style forums, group scheduling, document management, and news services are available from all four software vendors. From the way these companies are organizing their product offerings, and adding IMAP to their mail services, it's clear that IMAP or a technology that offers similar features is required to enable open, standards-based collaborative computing via the Internet.
All these products are
worthy contenders. However, since each server has some unique features and lacks some others, you might just want to wait for the next round of upgrades. If you must move to IMAP immediately, look for the available features that are most important to you. The three products we tested under NT were more complete than SunSoft's Unix-only server. Fujitsu's Teamware Mail is currently the best of the bunch.
Product Information
AltaVista Mail Server 97 2.0B...................$495 for 250 users
AltaVista Internet Software
Littleton, MA
Phone: 508-486-2700
Internet:
http://altavista.software.digital.com/
Circle 1058 on Inquiry Card.
Put Your E-Mail on the IMAP
