SMTP Mail Servers for NT

Get a head start evaluating Internet mail packages.

Joel Sloss

June 30, 1996

21 Min Read
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Get a head start evaluating Internet mail packages

Internet mail with Windows NT? You bet. And my tests showed that Internetmail can be easy with packages such as Post.Office for Windows NT (Netscape MailServer for NT), MetaInfo Sendmail with POP3, NTMail, Krypton Internet MailServer (KIMS), and Ipswitch Imail. KIMS is the only product that provides truesecurity between servers across the Internet. Imail strikes a good balancebetween ease of administration and feature set. Each package has strengths andunique qualities. Your task is to select the package that best meets your needs.So you have to evaluate your requirements and line up the products head to headwith them. This cruise through the Internet mail course gives you a head startin the evaluation race.

Serving Up the Mail
To understand how Internet mail packages work and which one is best for you,you need to know about the basic transport mechanisms they provide for maildelivery. Internet mail's two major protocols are Simple Mail Transfer Protocol(SMTP), ordinarily for mail between servers, and Post Office Protocol 3 (POP3)for client/server connections. You usually need both.

The SMTP server sends and receives mail for your users and stores itlocally. This server also listens for connections from other SMTP servers. Theservers connect via TCP/IP port 25 using Telnet--the same service you can choosefor an interactive session with a host somewhere on the Internet. Once youconnect, a simple text-based exchange transfers the mail. This pushprotocol works reasonably well for servers that are always available.

In contrast, for machines such as workstations that can use Remote AccessService (RAS) to collect mail or that aren't always turned on, SMTP isinappropriate. Instead, to let the receiver decide when it wants the maildelivered, these workstations need a pull protocol. That's where POP3comes in. It lets a client connect to the server and receive mail on demand.

Besides providing the basic transport mechanisms for mail delivery, anInternet mail package needs to perform other essential functions efficiently.How the administrator needs to add, configure, and remove users is crucial, too.Even if the server runs perfectly, if it's difficult to administer, it won'twork well for you. Another consideration is that users can best handle someaspects of their accounts, so you need to know whether the server lets them.Also, the server needs to provide automation tools such as mailing lists andmail robots.

All the products I tested worked as advertised, sending and receiving mailthrough SMTP and POP3 correctly. All the POP3 servers worked properly with bothMicrosoft Exchange and Eudora as clients. Although I couldn't test scaleability,all the products performed well, and none used CPU excessively. These productsdiffered in installation, configuration, and features. Post.Office is by far theeasiest to install and configure, but it is nowhere near as rich in features asNTMail, which is well integrated into NT. NTMail's installation went well andthe product lets you make the most of its capabilities and those of itscompanion, NTList (an email list server). Be aware that NTMail's learning curveis steep. MetaInfo's implementation of Sendmail works well, but it seems bestsuited to UNIX users moving to NT.

Finally, note that all the products I tested are dedicated mail servers. Ifyou're implementing a broader-based solution (e.g., a Web server), you'll findthat some Web server products include a mail component. For example, Interwareby Consensys is a broad-based Web server product that includes SMTP and POP3services. Also note that you can implement an SMTP gateway instead of a nativeSMTP server. In this case, the SMTP mail is rerouted into another mail system,such as Microsoft Mail. See the review of MailNet on page 31 for an example ofsuch a gateway product.

Post.Office/Netscape Mail Server
When Netscape Communications wanted to license a mail server, the companychose's Post.Office. Netscape and offer this productin two incarnations, one for each company:'s is Post.Office, andNetscape's is Netscape Mail Server for NT. Either way, it's slick and easy touse.

Each company has its own packaging of the product. The versioncomes in single-platform versions--Alpha, Intel, or MIPS--on floppy disks.( also plans to provide a bundled version.) The spiral-bounddocumentation is good. It introduces the SMTP and POP3 protocols and givesstep-by-step instructions for several typical system configurations. Theapproach to installation can be a bit annoying if you want to simply get to it,but the instructions will be helpful if you need some hand-holding. Netscape'spackage provides the code on CD-ROM and bundles it for both the Intel and Alphahardware platforms. Netscape's manual is perfect-bound, but it's otherwisesimilar to's.

Installation is easy. The installer, InstallShield, has a wizard interfaceto navigate the process, which takes fewer than 10 minutes (although if yourinstallation needs name servers, configuring them can require up to an hour).

The first installation step is to agree to a lengthy license agreement (ifyou read it, you'll double your installation time). The server can run either onits own account or on the NT system account. The installer asks whether you havecreated an account; if you say no, the installer launches User Manager. Afteryou enter the usual name and company information, the installer asks the name ofthe domain that the server will service, the port that the integrated HypertextTransfer Protocol (HTTP) server uses for management, and a password for theadministrator account. The default port for HTTP is port 80, but if the machinehas an existing Web server, you can choose a different one.

After you specify the target directories, the installer copies files andmakes the necessary Registry entries. That's all. The installation is complete.Now, you need to create the user accounts.

The installer also acts as an uninstaller. It does a clean job of removingthe server, if necessary.

An impressive aspect of these packages is their configuration utility--yourWeb browser. The product uses Hypertext Markup Language (HTML) forms to managethe server, including giving users access to account configuration. To createand manage user accounts, you can get and fill out several forms that cover allthe topics an administrator needs to deal with. You can access these forms froma main Web page by connecting to the server using the port number you assigned.As an example, Screen 1 shows the Account Creation Form. These packages supporta finger server that you can turn on or off, multiple delivery addresses, anddomain-based security. You also get an automatic reply capability that includesvacation, reply, and echo modes. For tighter security, you can restrict accessto any account by domain. Once you create an account, users can access certainaspects of its configuration through the Web browser interface.

The Information Form provides a way to change passwords and finger replies.A user can set the auto-reply to vacation mode and enter the text. You canforward addresses, as with a UNIX .forward file.

With other forms, the administrator can configure security, includingsetting access limits to the configuration tool by domain. This feature canprevent outside users from accessing administration, even if they know thepassword. Configuration by email, is a feature that the administrator can enableor disable from the Security Page.

The SMTP Channel Options Form lets you set up an SMTP routing table, so youcan direct mail to smart hosts that can deliver mail your server can'tmanage. You can also tell your server how to behave when it receives a messageto an unknown local address.

All the Basic Features
Both versions are impressively easy to install and configure. They offer allthe basic features you need in an SMTP/POP3 server, lacking only optionalcomponents such as mailing lists. The packages run well under NT, and you canadminister them from any machine with a Web browser. Post.Office is available onUNIX platforms, too. I find that these packages are the best choice for gettingInternet mail up and running easily, particularly for the first-time mailadministrator.

MetaInfo Sendmail with POP3
MetaInfo's approach to providing an NT mail server was to port the UNIXstandard Sendmail program. Integration of the program into the NT environment isgood, but Sendmail still has the flavor of its UNIX past. So although it's lessfriendly than Post.Office or Mail Server, Sendmail can be an excellent choicefor UNIX administrators adding NT to their enterprise.

The product comes without printed documentation and only a small readme.txtfile on the media. This file prints out on four pages that cover basicinstallation and configuration. The version I have is on one 3.5" diskettein a CD jewel case. The insert in the case implies that the product is supposedto ship on CD-ROM or diskette.

You need some experience with SMTP to work with this product. However, afterinstallation, you can access an extensive Help file in Windows Help format.

InstallShield and a Wizard help you install Sendmail. The first operation inthe installation is branding the disks with your username and serial number. Ifyou don't enter a serial number, the product installs as a demo.

The installation program prompts for the machine's domain name. On mymachine, the program made an odd guess, combining the NT computer name and theTCP/IP domain name.

The installation process lets you select the account under which Sendmailwill run. The default is the Administrator account, but a pulldown box lets youchoose from any existing account. The account you select must have administratorprivileges.

Once you specify a target directory, the installer completes theinstallation. Completion includes copying files and creating a Program Managergroup for quick access to the Control Panel applets that manage the Sendmail andPOP3 servers.

Sendmail also has an uninstaller. It works well, cleanly removing theapplication and Program Manager group.

Sendmail's configuration differs dramatically from Post.Office's. Sendmailis integrated into the Registry and requires an existing user account for eachmail user. You add an account to a group called POP3 so users can log in to thePOP3 server to retrieve mail. This approach is fine if all users are alsomachine account holders. If not, this requirement adds a complication.

The biggest hint that UNIX is alive and well inside Sendmail is thatconfiguration uses a SENDMAIL.CF file. Screen 2 shows the configuration dialog,which sets various parameters for server behavior. Its contents are typical ofUNIX--hard to understand and very picky about format. If you're a UNIXadministrator, this file has the advantage of being a standard SENDMAIL.CF file;if you're not, it means a steep learning curve.

UNIX Shops Adding NT
MetaInfo's Sendmail with POP3 for Windows NT is an excellent choice for UNIXshops adding NT. This product will be familiar to UNIX administrators, and ittakes advantage of the NT Registry for user information and runs as afull-fledged service. If you aren't familiar with UNIX, this version of Sendmailwill probably not be a first choice. Either way, the product installs easily,works well, and can reduce the work of creating users if all users have accountson the server machine. (MetaInfo promises to release a fully Windows-orientedversion next.)

NTMail (and NTList)
NTMail can be overwhelming. The product offers so many capabilities that youcan have trouble getting a firm footing when you first encounter it. But it'sworth the trouble. NTMail provides an excellent set of tools for sending,receiving, and managing Internet mail under NT. I'm glad the product isavailable for free testing, because using it is about the only way to becomeacquainted with it.

NTMail distribution is exclusively over the Internet; a copy of the product(a .ZIP file of just more than 2MB) is available from By specifying NTMail witha Web search engine, you can find NTMail on some mirror sites. On these sites,you'll find testing keys that enable the product for 10 users. If you need totest the package for more users, you can request a larger key by filling out aform at the Web site.

Although NTMail comes with no printed documentation, you get MicrosoftWord-formatted files--each about 6MB!--that document NTMail and its Internetlist server, NTList. The NTMail manual file has 100 pages and is nicely laidout. The quality is the same as that of the printed documentation you get withother products. When you order NTMail, you can get a printed manual for $50.This manual offers both a fast track section and a step-by-step explanation. Thedocumentation is complete and of high quality.

Basic installation is straightforward. First, unzip the distribution file toa temporary directory. Then start the installer (setup.exe). An initialscreen requests the key. Entering it is probably the hardest part ofinstallation. The key is a mix of upper- and lowercase text and symbols. A Testbutton lets you check proper entry of the key before proceeding and ensure thatthe key provides sufficient capacity. Because the key is so difficult to type, agood idea is to select and copy it after you enter it, in case you need torestart the installation. NTMail installation doesn't use a wizard, so you can'treturn to a previous dialog to correct data entry.

All information--key, branding, domain, and target directory selection--isin the initial dialog. NTMail correctly determined my domain name, but chose thesmall DOS partition on my machine for the installation directory. Watch for thisproblem and change the drive if necessary. Because of the online documentationand extensive product feature list, NTMail requires much more diskspace--30MB--than its competition. Be sure you have enough space availablebefore you start installing.

Once the file-copy process is complete, the installer updates the Registryand adds a couple of counters to the NT Performance Monitor, a nice touch. Setuppauses for confirmation before it updates the Registry. Then, Setup offers tostart the NTMail server for you.

Among the files NTMail installs are three Control Panel applets: NTList,NTMail, and NTMail Users. These applets accomplish all direct serveradministration. NTMail also supports mail-based administration, which isparticularly useful for end users. They can set up mail forwarding and vacationmessages, for instance.

The documentation includes examples of using Web pages to send controlmessages to the server with Mail To:. So, although NTMail doesn'tdirectly support Web browser access, with a little work, you can use it over theWeb.

Becoming a competent NTMail administrator takes time. Most things you willever want to control are configurable, as you see in Screen 3.

The product is highly automated. The main configuration activities are useraccount creation and various naming adjustments for such things as aliases anddomains. The main NTMail Control Panel applet offers access to all functions,and the NTMail Users applet offers a subset.

At the cost of ease-of-use, this product departs from the pack by providingmore capabilities. NTMail offers all the basic functionality of thecompetition--and more. For example, one potentially powerful feature isAuto-launch, which lets the server launch an NT application in response to anemail message. So an NT administrator can control a variety of programs on an NTbox without a realtime connection to the machine. Only your imagination limitsthe potential for Auto-launch.

The biggest difference between NTMail and the other servers in this articleis its direct support of a sophisticated Internet list server, NTList. A listserver (or list processor) automates the mailing of messages to a list ofrecipients at one address. Although this process sounds simple, managing a largelist is not trivial. Issues of subscription and desubscription, moderation(determining whether a message will make it to the list), limitation of contentand size, and other user-management features come into play. NTList addressesall these issues admirably. Although NTList is a separate product, it's bundledwith NTMail, and you install them at the same time. If you need a list server,this well-planned application will fit the bill.

NTMail also supports automation in the form of mail robots. Theseapplications give you several ways to process mail messages. Three examples areavailable on the distribution Web site: Hypermail, Dumpmail, and Conpage.Hypermail converts a sequence of messages into a Web page, allowing digests ofmailing lists to be Web-accessible; Dumpmail puts messages into an arbitrarydirectory; and Conpage accesses a paging terminal and sends a message based onthe subject line.

A Power Tool for Mail
NTMail and NTList are an administrator's power tools. They can do almostanything with email.

List services, robots, and extensive configurability make this product wellsuited to an enterprise that heavily relies on email for communications. NTMailis a professional Internet mail suite that won't disappoint you.

Krypton Internet Mail Server
The distinguishing feature of KIMS is that it has secure Internet email. Byusing Extended SMTP (ESMTP), KIMS can provide mail encryption across theInternet without requiring a special client. Two servers negotiate theencryption when they encounter each other.

Clearly KIMS developers focused on the product's technical quality. Theinstallation is functional, but bare bones. It uses Microsoft Setup and asksonly for a directory and a few options before completing. The default directoryis SMTP, and the entire installation in this directory takes about 170KB. Theinstallation program starts the KIMS service before end. Setup also acts as theuninstaller.

You administer KIMS through a simple Control Panel applet that is also astatistical monitor. It provides regularly updated numbers on mail-in, mail-out,and server up time. You can leave the applet running on the desktop to keeptrack of the server.

You can enter a few parameters from the applet, as Screen 4 shows. You canspecify an outgoing gateway. If you want your mail routed through a particulargateway rather than delivered directly, you define that gateway here. Threeother parameters relate to the Outgoing Mail Queue: OMQ Interval specifies howoften you want the server to check the queue for outgoing mail, OMQ Retriestells the server how many times to attempt delivery before giving up, and OMQRetry Delay defines the time between tries.

Checkboxes let you enable or disable server features. The Secure checkboxtoggles the KIMS secure mail features. If you turn off this box, KIMS behaves asan ordinary SMTP server. KIMS supports both node- and domain-relay functions. Ifyou enable node relay, the server forwards mail to a different server in yourdomain. If domain relay is on, the server forwards mail to another domain. Thedefault, which defines normal server operation, is to have both relays on.

Turning off ESMTP will also disable secure mail. This consequence isunintended, because one use of ESMTP is to negotiate encryption functionality.The ESMTP-based EXPN function lets you expand mail groups. KIMS is tightlyintegrated into NT's Registry, so KIMS can use NT groups as mail groups. You candisable this feature for a more secure, though less convenient, arrangement.

Features and Functions
KIMS supports mail forwarding and auto-reply. Forwarding works like it doesin the UNIX version by looking for a file called .FORWARD in the user'sdirectory. This text file contains only the address for forwarding.

KIMS also lets users configure features by email. A special user calledMailBot receives and processes control messages to configure user accounts. Touse MailBot, the user sends a specially formatted message to MailBot@host. Thesubject line contains a verb, set or clear, and a parameter, forward, reply, orpassword, to act on. The values for the command go in the body text. The replyfunction is auto-reply. The password function lets users set a POP3 passworddifferent from their NT account password. Anyone who will use the POP servermust have the Logon Locally attribute set. A good idea is to create a POP3 usergroup and set the attribute for the group.

User reports I've heard say performance is excellent. The developerscarefully wrote KIMS to use only Win32 calls, so it's a true and complete 32-bitapplication that can take full advantage of NT's multithreading capability.

Security Is the Key
The obvious advantage KIMS has over the competition is its ability to usepublic-key encryption to transfer mail securely across the Internet. When twoKIMS servers meet, they announce their encrypted mail capability and negotiatean encryption level. Then they can exchange keys and encrypt and decrypt themail. Traffic on the Internet is encrypted, but traffic from server to client isnot. A sniffer on your LAN can read the plain text mail.

KIMS comes in three versions: Standard, which has no encryption butsupports ESMTP; Domestic, which supports 40- and 80-bit key encryption and bothsingle and triple DES standards; and Export, which can do only 40-bit keyencryption. Legal limitations exist on the export of encryption technology, sothe 40-bit key support of the Domestic version is for compatibility with theExport mode. The KIMS implementation of secure mail--called Secure SMTP, orSSMTP--is proprietary, but it's based on standard ESMTP protocols, so theproduct is 100% interoperable with other SMTP servers.

Secure Mail Across the Internet
KIMS is technically excellent. It's unique in providing true secure mailacross the Internet, allowing users to be comfortable with the Internet as anenterprise mail transport. Because the focus is on technical quality, KIMS isless slick than its competition. But if you need high reliability, topperformance, and secure mail transfer, choose KIMS.

Ipswitch IMail
Ipswitch IMail is a thorough package that offers many of the same featuresas NTMail. However, Imail is easier to learn and administer than NTMail. IMailincludes a variety of servers besides the SMTP and POP3 servers required to dothe basic job. In addition, IMail can pipe mail messages into external programsfor automated mail response, list server, and other messaging applications.Unlike the other products reviewed here, IMail has a mail client.

IMail uses Microsoft Setup for installation, which is a quick and easyprocess, with two dialogs for information. Setup needs to know your machine'sfully qualified domain name and the target directory for installation. Itdefaults to IMAIL in the first partition. Once the file-copy procedure iscomplete, Setup reminds you to make a new emergency repair disk because IMailadds a security key to the Registry.

You administer IMail through a combination of the IMail User Manager foradding and managing users and a Control Panel applet that starts, stops, andconfigures the various servers. The User Manager is a two-pane application.Users are in the top pane, and mail aliases are in the bottom. Three selectionson a button bar let you add, modify, or delete a user. Selecting Add or Modifyinvokes a User Properties dialog that you can use for either function.

IMail comes with a finger service that lets a finger client connect to andretrieve information about a particular user. The traditional UNIX fingersupports a user-generated text file called a plan file. IMail handlesplan files, storing them in the user's directory as PLAN.IMA instead of astraditional UNIX .PLAN files. You can create and edit .PLAN files from the UserProperties dialog. One unique feature of IMail is a simple "rules"capability that lets the server direct mail according to the content of themail's header. The rules are simple searches in a message's from, to, subject,or sender lines. To manage mail addressed to a particular user, IMail followsthe rules in the RULES.IMA file in the user's directory. A rules editor is partof the User Properties dialog.

In addition to supporting the traditional auto-reply, IMail has a moresophisticated version called InfoManager. InfoManager can respond to messagesthat include a "subcategory" designation. For example, if yourorganization uses an [email protected] account to send information automatically,InfoManager can expand the system's capabilities by offering subcategoryresponses. A typical scenario involves sending a reply to the info account witha list of possible messages. InfoManager instructs the correspondent to sendmail to info-support@ for support and [email protected] forsales. These messages end up in the same place, but InfoManager replies with adifferent message for each. You can combine this capability with rules to makeit even more powerful. This useful feature will make setting up an email-basedinformation system quick and easy for any organization.

The User Properties dialog lets you disable the finger server on a per-userbasis. This capability is a nice confidentiality feature.

Another interesting approach in IMail is a remote configuration programcalled IMail User Utility. It lets users modify their accounts withoutadministrator intervention. The program communicates through TCP/IP, so you canuse it anywhere you can make a connection to the server. The User Utility looksa lot like the User Properties dialog, though it lacks a few options. Users canchange their POP server passwords (unless you go through the User Manager anddisable this capability user by user) and modify their forward and plan files.With the rules editor, users can set rules for mail delivery and enable ordisable the auto-reply program. Users can do almost anything without help.

The IMail Control Panel applet involves more than just SMTP and POPservers. You see six buttons, each for a service. They include a standard UNIXWhois server, a finger server, a password server, and a log server. The passwordserver provides support for the Eudora mail client password capability. Thisfeature is good if your organization has chosen Eudora. The Log Server logsserver activity, and you can view its log file from this dialog. Screen 5 is anexample of one of the six service dialogs you can access from the applet's mainscreen.

Because IMail can pass mail to other programs, you can use it with a listserver. List servers automatically receive and distribute mail and let youconduct discussion groups. Unlike NTList, the IMail list server is very simple,but it's still functional, and useful. If you want to write a more sophisticatedlist server, Ipswitch includes a .ZIP file with full source code for the listserver.

Thorough Selection of Servers
Ipswitch IMail is a solid product with a thorough selection of servers andusable utilities. It is not as slick as Post.Office or as automated as NTMail,but when you consider learning curve and sophistication, IMail's cost/benefitratio is excellent. The InfoManager feature alone will sell this product to someusers. IMail is easy to use and powerful.

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