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As mentioned earlier, Mail*Hub lags in the realm of Internet security support and security. For example, it doesn't support the new SMTP AUTH system, which lets a mail system authenticate a user before accepting mail from him or her for relaying, nor does it support mixing TCP/IP addresses and mail addresses as part of the antirelay rules.

ISOCOR N-PLEX Connect
ISOCOR, another familiar name in the e-mail backbone business, is at the forefront of NT technology with its N-PLEX Connect. Built from the ground up as a Windows NT product, and running exclusively on NT, this messaging switch reflects ISOCOR's great experience in moving messages around. Although its older N-PLEX Hub product provides greater messaging system support, ISOCOR considers N-PLEX Hub a legacy product, and we were told that its resources are going into the new Windows NT N-PLEX Connect line.

N-PLEX Connect doesn't stand alone. It requires a directory server to maintain all user information and some configuration data. For this, ISOCOR brought out its Global Directory Server (GDS) for Windows NT. GDS also runs on six Unix variants, but because N-PLEX Connect runs only on NT, we also looked at GDS on NT. We loaded N-PLEX Connect on one system and GDS on another, just to prove that they could operate equally well in a distributed environment.

Distributed management is N-PLEX's greatest strength. The products we tested can be fully managed using the Windows-style Explorer, so we were able to change the user and messaging system configuration from Windows systems around the network. Some network managers might feel limited by the requirement that the managing system be a Windows PC. For example, this stipulation means you can't telnet in from a cyber cafe and monitor things.

Our testing showed the possibilities for configuration and control within the ISOCOR message switch to be extensive. (See "Testing Task List" at left for specifics.) The only difficult part is knowing where to make a change. Do we go to the GDS or to the N-PLEX Connect configuration? And if it's in N-PLEX Connect, is it in the GUI or is it hidden with all the elaborate knobs in the NT Registry? Answering these questions entails learning the product, and while these difficulties aren't insurmountable, it wasn't always obvious what we had to do when. The documentation was good; we needed a couple of supplementary documents to wade through the setup, but it wasn't very difficult.

While N-PLEX Connect demonstrates some weaknesses in regard to configuration, our tests showed it to be a standout when it comes to managing multiple cooperating mail switches from a single location. While Mail*Hub has some cross-hub configuration features, the ISOCOR architecture makes keeping hubs in sync fairly easy (as long as you don't have to dive into the registry). For example, we were able to add a second ISOCOR N-PLEX Connect system into our configuration for failover purposes in less than an hour, once the original configuration had been established. This is a very useful feature that distinguishes N-PLEX Connect from the other switches we tested. While you could run PMDF on a Unix or OpenVMS cluster to get the same failover capabilities, the ISOCOR switch lets you handle different configurations from the same interface simultaneously.

Installation and setup of the ISOCOR N-PLEX Connect server was fairly laborious, primarily because the product insists on integrating message switching with directory services. Even though N-Plex doesn't talk to the PC-LAN-based mail systems (cc:Mail and MS Mail), it still took the ISOCOR team two days to put in all the links in our Exchange and Notes servers. In fact, they barely finished in time. This was partly due to the hardware in our lab: The Pentium 166 systems weren't fast enough to run N-Plex's gateways properly. Of all the systems we tested, ISOCOR's had the roughest feel. For example, the N-PLEX Connect Administrator's Guide (at more than 450 pages) thoroughly described the installation procedure but provided little conceptual information on how the pieces fit.