SMTP Server Roundup

Choose a product to help you build a reliable enterprise mail system

Editor's Note: Windows NT Magazine is solely responsible for the benchmark results in this article. Send comments or questions about the benchmark results to John Green at [email protected].

When you sit down at your desk in the morning and prepare for the day's challenges, what's the first thing you do? If you're like most of us, you'll answer, "Check my email." Email has become indispensable for business, and productivity and work routines are disrupted when email systems go down. Every enterprise wants a reliable mail system that supports the mail management and distribution features employees want and that can grow with the company. This month, I review six SMTP mail servers that are suitable for small, midsized, and, in a couple of cases, large companies. I don't review messaging suites such as Microsoft Exchange Server and Lotus Notes but focus instead on products that serve companies with modest requirements. (Messaging suites add workgroup features that many companies don't need, and such products usually support fewer users on a given hardware platform.)

To select six servers for review, I looked at mail servers that have a few basic features and target small to midsized businesses. In addition to the requirement that the mail server must run under Windows NT, each server must support the three basic mail protocols: SMTP, POP3, and Internet Message Access Protocol 4 (IMAP4). For an overview of email protocols, see the sidebar "Electronic Mail Standards," page 128. Each server also must include a list server to support a variety of business communication needs. Although I didn't require it for inclusion in the review, I looked for the ability to authenticate access to user mailboxes with a NT user ID. I also looked for telephone and email technical support.

In this review, I first describe the key feature set for each product and my experience installing and configuring the product. Table 1, page 126, compares the six products' important features, and Table 2, page 127, summarizes product pricing. I used Microsoft Outlook Express 5.0 and QUALCOMM's Eudora Pro 4.1, mail clients that support POP3 and IMAP4 access to the mail server, to test each product. I tested built-in Web servers that support Web access to mail in those products that include this feature. Finally, I stress-tested each server with a workload consisting of SMTP and POP3 transactions to derive a metric that lets you compare the servers' maximum throughput on a given hardware platform.

Mail and Authentication Options
Although all the systems I tested had good feature sets, some features stood out. For example, Ipswitch's IMail Server 5.0 and Gordano's NTMail can both automatically enable email support for NT user accounts, which saves administrative overhead. All six products support alternatives to sending a plain-text password across the network for POP3 and IMAP client access, although Stalker Software's CommuniGate Pro and ISOCOR's N-PLEX Global 4.0 have the most complete support for secure authentication standards.

Documentation
In an ideal world, products work reliably with an intuitive user interface (UI) and need no documentation. But in the real world, documentation often makes the difference between struggle and ease of use. All the products I tested include detailed and usable documentation. Five of the products make their documentation available in a printable electronic format—Portable Document Format (PDF), Microsoft Word, or DynaText. With the exception of CommuniGate Pro, whose documentation is available only in HTML format, the products ship with printed documentation.

Installation
None of the products I tested were difficult to install and configure for basic operation. All use an installation wizard to install software components. NTMail and Rockliffe's MailSite 3.3.1 were the easiest of the group to install because they both require minimal additional configuration after the installation wizard completes. N-PLEX Global's installation wizard installs only the product's Management Center; you must install mail support as an additional installation procedure.

Configuration and Management
The six products that I tested differed significantly from one another in configuration and management. MailSite was the easiest to administer, partly because of the MailSite Console's Explorer-like interface, and partly because of the product's relative lack of tuning options. CommuniGate Pro's Web-based administration tools were also easy to use and offered a useful variety of performance-tuning options. QUALCOMM's Eudora WorldMail Server 2.0 and N-PLEX Global both have an Explorer-like interface that is similar to MailSite's, and WorldMail Server and N-PLEX Global offer a variety of useful configuration and performance-tuning options. IMail's primary administration tool also offers an Explorer-like interface, but you can't use the tool remotely.

Remote Web-based administration is possible with IMail, although some loss of functionality exists in comparison with IMail's GUI tool. NTMail's Web-based administration was a little more cumbersome to use than CommuniGate Pro's but was more complete than IMail's. Except for IMail, each product lets you use the same tool for local and remote administration.

Differences between the products were also apparent in the type of mail accounts each supports. In addition to server-based mailbox accounts, which each product supports, all products except WorldMail Server support mailboxes that use NT user account authentication. CommuniGate Pro, IMail, and NTMail also support mailboxes that rely on an external database; MailSite includes this support at additional cost.

Mail Access
I found no significant differences between the products for POP3 and IMAP access with Outlook Express and Eudora Pro. CommuniGate Pro, IMail, and NTMail also offer Web-based mail access as a standard feature, although I was less than impressed with NTMail in this respect.

List-Server Features
CommuniGate Pro, MailSite, and IMail include full-featured list servers. NTMail includes a limited-use list server, and you can purchase NTMail's companion product, NTList, separately as a standalone list-management server. N-PLEX Global's and WorldMail Server's list servers can't reflect digested lists to members but are otherwise functional products.

Performance Testing
I performed mail-server benchmark testing in partnership with Client Server Solutions. CSS produces Benchmark Factory, an NT-based performance measurement and benchmarking tool that supports a broad spectrum of benchmark tests. (For more information about Benchmark Factory, go to http://www.benchmarkfactory.com.) I tested each of the mail servers with a mix of SMTP and POP3 transactions. Figure 1 combines the test results for all six products in one graph.

I tested each SMTP server package on a Compaq ProLiant 6500 quad-capable server configured with two Pentium Pro 200MHz processors and 256MB of RAM. I installed the programs to a RAID 5 array of seven Seagate Cheetah 9.1GB hard disks connected to a Compaq Smart-2DH Array Controller. Two HP Vectra XU 6/200 Pentium Pro 200MHz computers with 128MB of RAM generated the client workload. A Compaq Netelligent 5506 100Base-T switch was the network's heart.

I used Benchmark Factory's POP3 benchmark to devise a test for this review. For each server, I ran the test at varying user loads—from 100 users to 1000 users in 100-user increments. I generated the test's think time (i.e., how long each simulated user waits before executing the next transaction) randomly by using a negative exponential distribution with a 10-second mean. Because this think time is short, each simulated user generated a much higher workload than even the most active of email users would generate. Each time I repeated the test, a simulated user sent mail randomly to the other simulated users that participated in the test run. I intended this transaction mix to simulate an accelerated heavy-usage pattern for a POP3 user. In such a pattern, the POP3 client periodically connects to the server to check for new mail, download the mail, and delete the messages from the server. The benchmark test consisted of the following mix of transactions:

Results
Benchmark Factory measures the average number of transactions per second (tps) for each user load tested. As Figure 1 shows, with the exception of IMail, all the servers had comparable throughput for between 100 and 300 simulated users. At the 400-users level, NTMail's performance begins to drop behind the pack. At 400 users and above, a spread in performance is evident, with MailSite topping out at more than 76tps. N-PLEX Global placed second at almost 64tps, and CommuniGate Pro follows closely at 60.3tps.

Five of the six servers let NT user IDs and passwords authenticate access to mailboxes. The testing shows that using NT authentication can have a significant negative impact on overall POP3 mail-server performance. Because WorldMail Server doesn't support using NT accounts for mailbox access, I ran the primary series of tests with each mail server's user ID and password scheme. I ran additional tests in which IMail and MailSite used NT local machine accounts to authenticate mailbox access. IMail's throughput dropped to 58 percent of its throughput rate with native IMail authentication. For MailSite, the throughput cost of using NT account authentication was even greater: 48 percent of the throughput rate I measured with native MailSite authentication.

To help you better understand the test results, and to propose an explanation for the anomalous data point in the MailSite test results, let me explain SMTP mail delivery. SMTP mail delivery to a user mailbox is a two-step process. When a mail message first arrives at the server, the server places the message in a delivery queue. Messages usually travel from this incoming mail queue to their final destination (e.g., a local mailbox or another SMTP server) in a first in/first out (FIFO) sequence. The relative priority that any mail server gives to the SMTP receive operation in relation to the SMTP deliver operation is a function of the server's resource allocation bias and any tuning parameters available in the server. Of the products I tested, only CommuniGate Pro specifically lets administrators specify the maximum number of local delivery threads that mail servers can use. MailSite is the only product I tested that didn't provide a mechanism for performance tuning. All the other products let an administrator specify the maximum number of threads that the server can use. During benchmark testing, I observed that local mail delivery from the SMTP queue into user mailboxes would continue for a time after the end of a particular test run. To adjust for this phenomenon in CommuniGate Pro, I specified 25 local delivery threads. The other tunable products let me specify a number of threads for SMTP protocol use, but I couldn't specifically allocate the threads to local mail delivery.

The tuning bias can affect benchmark results in many ways. In MailSite, I observed that local delivery continued for a significant time following the end of a benchmark test run. MailSite apparently gives an absolute priority to SMTP receive activity and performs local delivery with the leftover system resources. As a result, under very high SMTP receive loads, no local mail delivery would occur. The absence of local mail delivery contributed to efficient SMTP transaction processing during the benchmark test and to efficient POP3 client transaction processing because the mailboxes had a high probability of being empty. In a conversation I had with Rockliffe's technical support department, the technician confirmed that problems with SMTP receipt and delivery processing in MailSite 3.3.1 cause delivery-queue backing under heavy loads. Rockliffe reports that it has resolved this problem in version 3.4.3.

For CommuniGate Pro, tuning to add local delivery threads gave the server a bias away from absolute SMTP receive priority. That is, allocating more resources to local delivery processing takes resources away from receipt processing. A reasonable assumption is that CommuniGate Pro would have scored higher had I configured fewer local delivery threads.

Keep in mind that with a 10-second mean time between transactions, the stress-testing load was at least an order of magnitude heavier than any real user would generate. Although the test generated an unrealistically heavy load, the results illustrate a need for vendors to tune their products to handle those exceptional loads that can sometimes catch a mail-system administrator by surprise.

Recommendations
The testing makes clear that I can't recommend one product for all situations. Despite performance variations, each SMTP server has plenty of throughput capacity for small to midsized organizations. For the small price-conscious company, WorldMail Server is a great value. With support for Lightweight Directory Access Protocol (LDAP) clients, a list server, and plenty of performance, WorldMail Server more than meets the needs of small organizations. Large companies would do well with either CommuniGate Pro or MailSite. MailSite posted the highest maximum throughput of the group, was the easiest to install and configure, and has the lowest price for more than 100 users. CommuniGate Pro offers solid performance and adds a good Web-based mail client, a more feature-rich list server than the other products, and the ability to add multiple-server support for growing organizations.

CommuniGate Pro
CommuniGate Pro is a full-featured, scalable SMTP mail and list server. Standard features include SMTP Internet mail support with extensions, Web access to mail, and support for POP3 and IMAP4 clients. The software has features to protect against unsolicited commercial email (UCE), including blacklisting and return path verification. Remote POP (RPOP) support lets users specify POP accounts on other mail servers for CommuniGate Pro to poll periodically. The RPOP feature also supports organizations that receive all user mail in a single-mailbox account (i.e., unified domainwide account) that the organization's ISP provides. RPOP periodically polls the ISP account and distributes mail messages from the unified account to users' CommuniGate Pro mailbox. CommuniGate Pro's multithreaded design supports simultaneous access to a mailbox from multiple POP3 or IMAP4 clients. You can use NT user accounts and CommuniGate Pro-created accounts to authenticate user mailbox access.

The software implements an LDAP server for access to account and other information that the Central Directory database contains. Application Configuration Access Protocol (ACAP) support lets IMAP and POP clients retrieve configuration and preference settings from CommuniGate Pro. The Password Modification Protocol (poppwd) lets supporting clients change the password for mailbox access. Because a mailbox owner can use either an NT account password or a CommuniGate Pro password for mailbox access, poppwd checks to see which password is in use, then changes the password to the new password. CommuniGate Pro supports a number of secure client authentication protocols, including Authenticated Post Office Protocol (APOP), IMAP-AUTH, and CRAM-MD5.

Installation. CommuniGate Pro is available for a variety of platforms in addition to NT, including several UNIX variants, Apple MacOS X Server (aka Rhapsody), and Windows 9x. The software ran well on the Windows NT Magazine Lab's 256MB test server.

Installation isn't difficult. After you unzip the installation files, a README file guides you through the initial software installation. Installer.exe prompts you for two file paths, for CommuniGate Files and CommuniGate Pro Directory. Mailbox and queue files reside in CommuniGate Files, and program executables reside in CommuniGate Pro Directory. The installation process creates a Postmaster account that you use to set up accounts and configure the system. The system generates a random password for the Postmaster account. Rather than displaying the password, the installation instructions direct you to find the randomly generated password in a text file in the Accounts directory. If you choose to change the password to something easier to remember, you must restart CommuniGate Pro before configuring the system. CommuniGate Pro runs as one NT service, in contrast to the other mail servers I tested for this review, which installed multiple services.

Documentation. CommuniGate Pro's documentation is Web-based and contains clear descriptions of the various components of the product. However, during my testing I wished I'd had a PDF version of the manual, and a way to search the entire documentation set for keywords.

Configuration and management. CommuniGate Pro incorporates a Web server to support system administration and user-account management. Connecting to port 8010 brings up the system administration pages, which are logically organized into four groups: SETTINGS, Accounts, Domains, and MONITORS, as Screen 1 shows. To complete the basic configuration, I entered an email domain name and created mailbox accounts. If you convert from another mail system, CommuniGate Pro will use information in a tab-delimited file to create numerous mailboxes. With only a few minutes' effort, I used Microsoft Excel to make a tab-delimited file that created 1000 users.

The software's default tuning parameters are suitable for the typical loads that a small business generates. However, I planned to stress the server with a heavy load, so tuning was necessary. Because I planned to simulate up to 1000 concurrent users for benchmark testing, I configured 1000 SMTP receiving channels, 1000 POP3 channels, and 10 local delivery threads. The SMTP receiving channels support client connections sending mail to mailboxes in CommuniGate Pro. The POP3 channels support connections from POP3 mail clients. When the SMTP module receives a mail message, the module places the message in a delivery queue. The software hands off messages addressed to local users to a local delivery agent for delivery into a user's mailbox. The default number of local delivery threads (one) couldn't keep up with the rate at which the server received messages during heavy-load testing. With 10 delivery threads, local delivery of mail messages completed within 5 minutes after the end of the test.

POP, IMAP, and Web access. I used Outlook Express and Eudora Pro 1.0 to test CommuniGate Pro's POP3 and IMAP4 client support. Using both programs, I sent and received mail, created IMAP folders, and moved mail between folders.

The software's Web access was a pleasant surprise. Stalker fully integrated Web support into CommuniGate Pro, and the support doesn't require a separate Web server. Using Microsoft Internet Explorer (IE) 5.0, I sent and received mail, sent and saved attachments, created IMAP folders, and moved mail between folders. The Web client displays entire messages in one pane, and you can scroll the pane to view the entire message. You can move between unread mail items in a folder without having to return to the folder view. You can mark messages as read or unread, flag messages for attention, and undelete messages that you marked for deletion. The software also supports user Web pages when the mail administrator enables this feature for a mailbox account. Web access to email lets users access functions that aren't available through most POP3 or IMAP4 clients, including the ability to set an automatic reply message and to control the appearance of the mail viewing and composing screens.

List-server features. CommuniGate Pro includes a full-featured list server. The software supports moderated and unmoderated lists and lets you define who can subscribe to an unmoderated list. Users can select message delivery when the list receives the message, delivery of periodic message digests, or delivery only of the digest table of contents. Index subscribers can use the Web access facility to view messages. You can configure lists to accept messages from anyone, from list members only, or from users in the same mail domain. In addition to letting users send a subscribe email to the list, the mail administrator can import member addresses from a text file.

Performance. CommuniGate Pro performed well in my testing, delivering a third-place maximum throughput of 60.3tps in the benchmark test. Unfortunately, CommuniGate Pro also holds the distinction of exhibiting the worst drop in performance when the load increased beyond the point of best performance; the drop was such that the software couldn't successfully complete the last step of the test. I might have been able to cure this behavior with a little additional tuning, perhaps by specifying fewer threads in support of delivery of queued mail to local mailboxes, but I didn't have the time to test this theory. In CommuniGate Pro's favor, the software was the only product that let me configure local delivery threads. This capability lets mail administrators balance system resources that are dedicated to receiving mail for the queue with resources that deliver mail to a user's mailbox.

Final valuation. CommuniGate Pro is the most full-featured of the six mail servers I tested. The software comes with a good Web-based mail client, LDAP support, a full-featured list server, and plenty of performance and scalability. Mailbox for mailbox, of the six products I tested, only MailSite costs less than Communigate Pro, and MailSite lacks some of CommuniGate Pro's key features. CommuniGate Pro is a great value.

Eudora WorldMail Server 2.0
WorldMail Server is an Internet mail server that supports SMTP with extensions, POP3, and IMAP4. Similarly to the other five products I tested, the software supports multiple mail domains and incorporates a list-server function. QUALCOMM based WorldMail Server on N-PLEX server technology, which QUALCOMM purchased from ISOCOR and enhanced. WorldMail Server includes LDAP and X.500 directory support but doesn't support mail domains distributed over multiple servers.

WordMail Server includes an autoconfiguration service that lets Eudora email clients automatically retrieve configuration settings from the server. This capability eliminates the need to enter setup information during installation of the Eudora mail client. The software's distribution package includes a version of the Eudora Lite POP-IMAP client that uses WorldMail Server's autoconfiguration service.

WorldMail Server lets systems administrators define shared folders with an associated email address and allow specific users access to the shared folders. You can use this capability to let multiple users access one copy of a message in the shared folder.

The software supports only one mailbox type and can maintain two passwords for each mailbox: a clear text password and a password for use with secure connections using APOP or CRAM-MD5. WorldMail Server doesn't support NT account authentication, nor does it let you create mailboxes by importing accounts directly from an NT domain or local accounts database.

Installation. WorldMail Server's system requirements are basic. Despite the product's ISOCOR N-PLEX heritage, installing the software was easier than installing N-PLEX Global. WorldMail Server's installation program installed the WorldMail Management Center, Internet Mail Service (IMS), and Directory Service in one operation. Seven services support the product. The WorldMail and Message Store services support basic messaging capabilities. The Directory Service, Web/LDAP/x.500 Gateway, and Ph2LDAP Proxy services support Web access and directory services. The Remote Management Agent and List Management Agent services round out the services list.

The next steps in the installation process are to create one or more mail domains and users. I accomplished both operations easily by using the WorldMail Management Center.

Documentation. Rather than providing documentation for viewing with a Web browser or Adobe Acrobat, QUALCOMM uses DynaText 3.1 for online documentation. DynaText displays the table of contents for all the online manuals in the left pane, allowing easy scrolling between manuals. You can select a section from any manual, and the section will quickly display in the right pane. I found the product's documentation well organized and useful. The context-sensitive Help is informative and offers item definitions and usage examples. You can easily print large and small portions of the manuals from DynaText. Unfortunately, documentation text didn't display clearly until I adjusted the display size, and even then the display wasn't as clear as an Adobe Acrobat 4.0 presentation.

Configuration and management. WorldMail Server offers two interfaces for mail-system management. The first interface is the WorldMail Management Center, which Screen 2, page 133, shows. WorldMail Management Center is a Windows GUI program that supports full remote and local management of WorldMail Server. WorldMail Server's systems administration facilities are password-protected. After you supply a read-only or read-write password, the Management Center displays a hierarchical list of configured servers and their installed components in the left pane. Selecting an item in the left pane displays the item's objects (e.g., users) in the right pane. Right-clicking any item in either pane displays a menu of relevant actions, such as configure, add, or delete. Using the Management Center, I was able to quickly add a mail domain and users to the system.

You can create multiple accounts from text-file input with the software's bulk load utility, nibl.exe. The utility also lets you save and restore the complete WorldMail Server configuration information for backup and to use when you move or upgrade the server. In addition, the software lets you link to an NT account database to create mailboxes for existing users.

The Group Account Manager, a Web-based Java applet, is the product's second interface for mail-system management. You can use the Group Account Manager to manage users and distribution lists (DLs) and display selected domain configuration information.

WorldMail Server supports distributed management of mail domains. Within a mail domain, systems administrators can specify which mail users are authorized to administer the mail domain. The mail administrator can also restrict an individual administrator's access to eight specific domain attributes pertaining to accounts, mailing lists, and shared folders.

The software offers a good set of performance-tuning options. Administrators can specify the maximum number of SMTP send and receive threads and the maximum allowable number of concurrent client connections.

POP, IMAP, and Web access. Mail access using Outlook Express and Eudora Pro worked without a hitch in the software's POP3 and IMAP4 operation modes. I was able to send and receive mail, create new IMAP folders on the server, and move mail items between folders. WorldMail Server doesn't have a Web client for mail access. The software includes the Personal Account Manager, a Web-based Java applet that lets mailbox owners access the mail server from the Web to create automatic reply messages, configure mail-forwarding addresses, and change mailbox passwords.

List-server features. WorldMail Server includes a list-server feature that supports open, restricted, and moderated lists. The feature supports subscribe and unsubscribe commands and requests for subscribers and lists. The mail administrator controls who can join the list, who can distribute messages through the list, and who can request a list of members who subscribe to the list. The product doesn't support digested lists; the list server sends messages it receives to list subscribers upon receipt of the message.

Performance. The software performed well overall and had the fourth highest peak throughput—56.55tps. This performance is respectable.

Final valuation. For small organizations, WorldMail Server is the most value-priced product of the six I tested. Software pricing begins at $159 for 10 users. With LDAP support, a good list server, and plenty of performance, WorldMail Server gives you a lot of functionality for the money.

IMail Server 5.0
In addition to basic support for POP3, IMAP4, SMTP, and several SMTP extensions, IMail Server includes many features that are common to the other systems I tested. By letting users send and receive mail from any Web browser, IMail Server's Web-messaging component eliminates the need for a mail client. The product's Web-based administration supports remote account administration and system configuration. IMail Server also includes list processing and anti-UCE features. The software's LDAP directory interface lets mail clients query the directory for email addresses and other information.

IMail Server runs as several services under NT. The software runs one service each for SMTP, POP3, IMAP4, and LDAP protocols; one service for Web messaging; one service for the list server; and one service for the product's self-monitoring feature. IMail Server's self-monitoring service is a particularly interesting feature. The service monitors each of the IMail Server services, restarts failed services, and sends event notification by email or pager. You can configure the service to monitor other services, the default gateway, and disk space.

IMail Server supports three sources for user IDs and passwords that authenticate access to mailboxes, and the software requires that you select one of the three methods when you install IMail Server. You can base user accounts on the Windows NT Database, IMail Database, or External Database.

When you choose the Windows NT Database method, you enable email for all NT domain database accounts and let users use their NT user ID and password to access email. The software automatically creates new email accounts when you add new users to the domain accounts database. This option requires that you configure the IMail server as an NT domain controller, so that the mail server will maintain a copy of the domain accounts database.

When you choose the IMail Database option, the software stores accounts in the NT Registry. In addition to using the IMail Administrator to manage user accounts, you can also import accounts from the NT accounts database when you use the IMail Database option. However, accounts you import from the NT accounts database don't retain their password from that account—you must specify a password that the IMail Database will maintain.

External Database is IMail Server's third option to store user information and authenticate mailbox access. As with the IMail Database option, you use IMail Administrator to add and remove accounts from an external database. When you use an external database, you must write a DLL program to provide an interface between the mail system and the database.

IMail Server supports CRAM-MD5-based authentication protocols to help protect user passwords as they pass through the network. IMail Server documentation doesn't specify which secure protocols the software uses for client access. When I tried to use Secure Password Authentication from Outlook, the authentication operation failed. However, when I used Eudora Pro, IMAP use of the CRAM-MD5 authentication was successful. POP use of APOP also failed, but Remote Passphrase Authentication (RPA) was successful.

Installation. Installing IMail Server was easy. The setup.exe program asks for a target directory for the program and requires you to choose between IMail Database and Windows NT Database accounts and to verify the mail server's host name in the DNS system. The installation wizard gives you the option to add users immediately following the installation process.

IMail Server runs 10 NT services. Eight services are set at installation to start automatically. The installation program sets the Whois and Finger services to start manually. IMail Server installs services for SMTP, POP3, IMAP4, HTTP, and LDAP; logging; password changing that supports Eudora clients; and system monitoring.

Documentation. IMail Server ships with a printed user manual that is also available as a PDF document. The manual is comprehensive and well indexed and includes all the usual installation and configuration topics. In addition, the manual includes a description of Registry settings and of the files that IMail Server uses and documents the 10 command-line utilities that are available for scripting administrative tasks for special circumstances. The IMail Administrator program includes excellent Help screens. I used the Help facility to answer several how-to questions and found the information I needed quickly each time.

Configuration and management. IMail Server offers more options for systems administration than any of the other products I tested. The IMail Administrator program runs only on the mail server and provides a GUI for administering mail domains, users, aliases, and other common functions. As Screen 3 shows, the program's left panel presents a hierarchical view of the mail server and the objects the server includes.

IMail Server stores system configuration parameters in the NT Registry and installs a Control Panel applet to manage these stored parameters. IMail User Manager is an alternative GUI for managing user accounts. IMail User Manager's functionality is duplicated in IMail Administrator, but some users might find its presentation of user account management tasks easier to use than IMail Administrator's.

You can administer IMail Server remotely via the Web and by using the iradmin.exe remote administration utility. Iradmin.exe supports only basic user management (i.e., the ability to change passwords and add users and aliases). The Web interface lets systems administrators perform most of the functions that IMail Administrator supports but with a different UI.

IMail Server doesn't have a GUI to let you perform system tuning and administration tasks. Instead, IMail Server documentation tells you how to make changes to the NT Registry to accomplish these tasks.

When you want to import NT accounts, the software lets you select only accounts from the local accounts database. If you want to import accounts from the domain database, you must take another approach, such as extracting account names to a test file and editing the file to call the supplied adduser.exe command-line utility.

For large installations, IMail Server supports the use of several IMail Server servers working together in a peer relationship. Linking servers lets you configure one server for Windows NT Database mailbox configuration and configure additional servers for IMail Database or External Database.

POP, IMAP, and Web access. IMail Server's POP3 and IMAP4 access was unsurprising. I used Outlook Express to send and receive mail in POP3 and IMAP4 modes. In IMAP4 mode, I could create additional folders and move messages between folders. The LDAP server returned potential email recipients when I queried the server for a partial name.

IMail Server's integrated Web access is easy to implement and use. Web-access support doesn't require additional software, and you can configure the support for access at the standard TCP/IP port for HTTP traffic (i.e., port 80) or for another port if you have another Web server on your system. The Web interface lets you access all folders, create new folder hierarchies, and move mail between folders. However, the software contains no interface to LDAP services for locating email addresses.

List-server features. The product supports standard list-server features. For example, lists can be moderated or unmoderated, and users can subscribe and unsubscribe to public lists. Lists can also be private, so that the software rejects subscribe commands and the list administrator controls list membership. Messages users send to a list will either reflect to the members of the list immediately or collect for periodic distribution if you set the list to digest mode. However, list members can't choose their message delivery mode, as they can with many list servers.

Performance. IMail Server placed last in my performance testing, with a maximum throughput of just under 24tps. If you need maximum performance for large user loads or active mailing lists, consider another product. However, if those needs don't pertain to your organization, you needn't be concerned about IMail Server's throughput limitation. Despite the product's relatively slow performance, it has plenty of speed for the average organization.

Final valuation. IMail Server has many features that the other products didn't have—including service monitoring and automatic mail account creation for NT users. At $1495, IMail Server was also the most value-priced package for unlimited client connections. With a good list-server feature set, a Web-based mail client, multiple-server support, and a host of other features, IMail Server can likely offer the functionality you need.

MailSite 3.3.1
MailSite implements SMTP with extensions, POP3, IMAP4, and LDAPv3. The product implements secure client access with APOP, AUTH, and AUTHORIZE for client support. The product is an enhanced version of Freeware IMS, which the European Microsoft Windows NT Academic Centre (EMWAC) developed. (EMWAC is a consortium that Microsoft UK, Research Machines, and the University of Edinburgh support.) MailSite supports several mailbox types that each use a different source for user IDs and passwords. You use a MailSite-specific password that the software stores in the NT Registry to access a Registry Mailbox. You use an NT user ID and password from the NT accounts database on the MailSite server to access an NT Mailbox. Database Mailboxes are an optional feature that lets an organization control access to mailboxes with user IDs and passwords that the software stores in an ODBC-compliant database. You must purchase Database Mailboxes separately.

MailSite has an integrated list server. You can extend MailSite's functionality by using Agents, which are programs or .bat files that run when MailSite modules process messages.

The product's Domain Name Synonym function is useful for companies that have multiple domain names and users who work within the context of several domain names. You can configure synonym domains in your main mail domain so that mail addressed to [email protected] is delivered to [email protected]. Other mail systems require you to define such aliases at the user level. The Domain Name Synonym feature saves a lot of administrative work, especially when you consider how much effort is necessary to define email aliases for each user in each domain name.

Installation. MailSite was the easiest to install of the six systems I tested. Rockliffe distributes the software on CD-ROM in a 6.7MB setup.exe file. The installation process lets you specify one location for Program and Documentation files and another location for the Spool file directory, in which MailSite temporarily stores mail in transit. After you enter the license key and specify whether MailSite services start automatically when the system boots, installation proceeds to completion. The installation process doesn't tell you that the default path for mailboxes—in which the software stores all user mail—is where you told MailSite to place the Program and Documentation files. However, you can use the Domain Properties page of MailSite Administrator to easily specify a different location for mailboxes. Rockliffe implements MailSite as a set of seven services under NT. The services comprise one service each for POP3, IMAP4, LDAP, and HTTP support; one service for incoming SMTP mail; one service for outgoing SMTP mail; and one service that supports remote management via the MailSite and Java consoles.

Documentation. The software ships with an easy-to-use spiral-bound MailSite Administration Guide and Windows Help files (on CD-ROM) for installation and administration. An electronic version of the Administration Guide in Word format also ships on the installation CD-ROM. The manual is thorough, easy to use, and clearly describes installation and administration tasks and procedures, MailSite architecture, and troubleshooting.

Configuration and management. You can install the MailSite Console, the product's primary, Windows-based, management console, on remote machines to remotely manage MailSite. In addition to the MailSite Console, you can use the software's Java Console and Web Console to manage mailboxes and mailing lists. Both the Java Console and the Web Console make use of MailSite's built-in Web interface, which I accessed by pointing my browser to port 90 on the MailSite server. The Web Console lets users change their password (including NT account passwords for NT mailbox users), forward their mail to another email account, and set up an automatic reply to incoming mail messages. Systems administrators can manage user mailboxes and mailing lists via either Web interface. Mailing list moderators can use the Web Console to approve list messages and manage list membership.

For activities other than mailbox or mailing list management, you must use the MailSite Console, which Screen 4 shows. Unlike other SMTP servers, MailSite offers no facility for performance tuning; you can't set a maximum number of concurrent connections or active threads. However, this limitation also made MailSite the easiest of the six products to get up and running.

Using MailSite to add user mailboxes based on existing NT domain accounts couldn't be easier. I used the MailSite Administrator program to select the Mailbox item under the default NTLAB.COM mail domain I created during installation. Until I selected the Mailbox item, which displays existing mailbox names, the Mailbox menu item Create New was dimmed. I was annoyed that I had to select the Mailbox item before I could use the Create New menu item. I assume that the reason for this extra step is that MailSite needs to know which domain you are creating a mailbox in. However, the program could handle this situation more flexibly, rather than leave inexperienced administrators wondering why the Create New menu item is not available. After you select Create New, NT Mailboxes, MailSite displays an NT domain user account list, with an option to display groups defined in the domain. Selecting one or more user accounts or groups lets you quickly create mailboxes for each selected user or member of a selected group.

I discovered one glitch in MailSite's operation. When creating an NT Mailbox, MailSite displays a list of local machine and domain accounts to choose from. When accounts with the same name exist in both the domain accounts database and the local accounts database, MailSite displays only the domain account. However, if a user tries to access the mailbox, MailSite requires the password to the local machine account.

An easier way to create NT Mailboxes exists. You simply create an NT local or domain group and configure the MailSite NT Mailbox plugin to create a mailbox for each member of the selected group. MailSite will check the group for any unresolved email addresses within the mail domain and automatically creates a mailbox the first time the user receives a message, or the first time the user attempts a POP or IMAP connection.

POP, IMAP, and Web access. When I used Outlook Express and Eudora Pro to test POP and IMAP access, I was able to send and receive mail, create IMAP folders, and move mail between IMAP folders. MailSite doesn't include a Web-based client to send and receive email.

MailSite became confused when the software accessed an NT mailbox based on a user ID that both the domain account database and the mail server's local accounts database defined. When you create NT mailboxes, if both a domain and a local machine account with the same name exist, MailSite displays the icon for a domain account but will use the local account's password to authenticate access to the mailbox. This situation can create confusion when the same user ID exists in the local machine accounts database and the domain database with different passwords.

List-server features. MailSite includes a powerful and flexible list-server feature that forwards messages sent to the email address of the list to each list member. The software supports moderated and unmoderated lists. You can configure mailing lists to reflect each message to the list members as the message arrives, or to collect messages and send them periodically (i.e., digest mode). In addition to letting users send subscribe and unsubscribe requests to the mailing list's email address, MailSite lets the systems administrator create mailing lists based on membership in an NT domain or local group, database query, or local server membership. A text-file based mailing list is another MailSite feature that lets you create and maintain a mailing list that you base on information external to the mail system.

Performance. MailSite's peak performance of 76.88tps at the 800-virtual-user level was the highest I measured in this group, but the transaction rate dropped markedly as I added more users. MailSite is completely self-tuning. The product can cope with a high volume of incoming mail while letting the local delivery queue accumulate messages for processing after the incoming load subsides. Overall, MailSite is an excellent performer.

Final valuation. MailSite has a lot going for it—a good feature set that includes LDAP support, a great remote-management facility, and top performance. Add to those benefits the lowest cost in this product group for larger organizations. Even though MailSite lacks a Web-based mail client, the product is a great value.

N-PLEX Global 4.0
N-PLEX Global is a sophisticated, scalable mail server. Although ISOCOR markets N-PLEX Global primarily to ISPs and large corporations, the product scales to small companies that want to take advantage of its full feature set, reliable performance, and compliance with a broad range of Internet mail standards and Requests for Comments (RFCs).

N-PLEX Global supports SMTP with extensions, POP3, and IMAP4. The product can support LDAP-based queries into the mailbox database and account replication with other LDAPv3-compliant servers in support of a centralized corporate directory; however, to take advantage of this functionality, you need to purchase ISOCOR's Global Directory Service separately. N-PLEX Global monitors mailbox disk usage for soft and hard quotas. N-PLEX Global's password policy management lets administrators require a minimum password length and allow use of uppercase, lowercase, and nonalphabetic characters in the password. N-PLEX Global stores user settings in a proprietary database structure, rather than in the NT Registry.

N-PLEX Global can use an existing NT account or a password that you create to authenticate user access to mailboxes. When you choose NT account authentication, the user's NT user ID becomes the default email address in the domain you create the mailbox in. You can create additional user email addresses as aliases in the default domain or any other domain that the mail server hosts.

Installation. I received my test copy of N-PLEX Global as a Zip library. After extracting the files, Setup guided me through the installation process and prompted me to provide a directory to install the files into and a password to use when I access administrative functions. As I let Setup reboot the system, I thought that this product was the easiest to install of all the products in this group. Then I tried to Telnet to port 25, the SMTP port, and couldn't connect. I experienced the same failure with port 110, the POP3 port. I decided to read the installation instructions.

I learned that Setup installs only the ISOCOR Management Center. I had to use Management Center to install Internet Mail. By expanding the view in Management Center's left pane and right-clicking the name of the server, I was able to see and select the Install option. The program remembered the original source path and displayed the optional components available for installation. I selected Internet Mail, and the IM installation wizard started. The wizard prompted me to enter a destination directory for mail files and choose another password for Internet mail administration tasks. After I entered the product serial number and license key, the wizard completed without requiring another reboot.

N-PLEX Global consists of seven NT services. The Mail Server, Mail Delivery Agent, Mailbox Monitor, and Message Store services support basic messaging. The software uses the White Pages synchronization service in conjunction with an LDAPv3 server, such as Global Directory Service. The software also installs the Remote Management and List Management services.

To complete the basic installation, I had to configure a mail domain and users. I expanded the IMS object in the left pane of Management Center, right-clicked Mail Domain, and selected the Add Domain menu. I typed in ntlab.com at the prompt, and the software added the domain object to the list. Adding individual users was not much more complicated. When I right-clicked the mail domain object ntlab.com, then selected Add, the Message Store User menu item displayed, and I could create individual users.

Documentation. When N-PLEX Global installs, comprehensive software documentation in PDF format installs in the program directory. You can print out the documentation. I found the table of contents for each manual in the documentation to be thorough and well organized. A Main Menu document for the four online manuals makes moving between manuals easy. N-PLEX Global's documentation is the most comprehensive and usable documentation set of any of the products in this review.

Configuration and management. A variety of account and mail-server administration options are available to N-PLEX Global users. Management Center, which Screen 5 shows, is the primary system administration tool. You can run Management Center remotely if you install the ISOCOR Remote Management Agent service on the mail server. Management Center displays a typical tree or hierarchical view of the system in the left panel. Right-clicking an item in the left panel displays a menu for that item. Selecting an item in the left panel displays objects created under that item in the right panel.

Management Center renders N-PLEX Global highly configurable. You can specify the number of concurrent send and receive threads for performance tuning. You can specify mail retransmission retry periods and direct your mail server to implement the N-PLEX Global-supported mail extensions and RFCs that you specify. Other features, such as the ability to specify the amount of free disk space that is necessary for mail-server operation, reflect N-PLEX Global's large-enterprise-class feature set. N-PLEX Global was one of the few servers I tested that supported this level of configuration granularity.

N-PLEX Global includes two Web-based management tools. One tool helps mailbox owners manage their mailbox account; the other tool assists mail-system administrators. Both tools are Java applets that require a Web server and require the ISOCOR Remote Management Agent service on the mail server.

ISOCOR supplies several utility programs with N-PLEX Global. The db_dump utility creates a copy of the mail accounts database in a readable text-file format. You can use nibl.exe to quickly dump and load large numbers of mailbox accounts.

POP, IMAP, and Web access. N-PLEX Global's POP and IMAP client access is unremarkable, and all the software's mail-management features work well. I was able to send and receive messages, create IMAP folders, and move messages between folders. ISOCOR supports Web access to email in N-PLEX Global with Web Express, a product that you must purchase separately. Because ISOCOR didn't build Web support into N-PLEX Global, Web Express requires a separate Web server to implement Web-based email.

N-PLEX Global doesn't include an LDAP server as a standard feature, and thus doesn't support LDAP queries to its directory. ISOCOR's Global Directory Service, a companion product to N-PLEX Global that you must purchase separately, is a fully LDAPv3-compliant server that adds client query support as well as LDAP directory replication with other LDAPv3 servers.

List-server features. N-PLEX Global has a flexible list-server feature that supports standard subscribe and unsubscribe commands, as well as who, which, and lists commands. The software supports moderated and unmoderated lists. Lists can be open (i.e., anyone can submit mail to the list) or you can restrict lists to mail from list members or to mail from the list moderator. For advanced list applications, N-PLEX Global lets you write your own list-management agent. The product doesn't support digested lists.

Performance. N-PLEX Global's peak performance reached a maximum throughput of nearly 64tps, the second fastest of the six mail servers I tested. In addition, the product was the only server in which throughput didn't decline significantly at loads higher than the point of maximum throughput. If you want steady performance under any load, N-PLEX Global is the product to buy.

Final valuation. N-PLEX Global is a robust mail server for high-end environments. Although the software is highly configurable with great remote-management capability, it lacks some key features, including LDAP support and support for digested lists in its list-server function. In version 4.0, I sense a vendor commitment to continue to support enhancements to email standards and maintain the high performance and reliability that the largest ISPs and businesses need. N-PLEX Global is by far the most expensive of the servers in this group, with a base price of $1000, plus $3 to $5 per mailbox. Large organizations should consider the product; other companies will be better off with one of the lower-cost packages.

NTMail
NTMail supports Enhanced Simple Mail Transfer Protocol (ESMTP), POP3, and IMAP4. HTTP supports Web access to mail and system administration functions. The product also supports the Finger and Passwd protocols, which let users publish information about themselves and let Eudora users change mail passwords from their mail client. NTMail supports three account types. For the first account type, you can use a password that the mail-server's Registry stores to create an NTMail account. For the second account type, you can define an NT group with the same name as the email domain to create an NT SAM database account for NTMail. For the third account type, you can store account information in a custom database. To employ the third account type, you must write a custom DLL to provide an interface between NTMail and your database. NTMail supports APOP and AUTH to provide secure client connections.

Installation. NTMail was one of the easiest to install of this group of products. The installation file is a single self-extracting executable file. When you run this program, the installation wizard starts. The wizard asks you to verify basic information such as mail domain name, server IP address, company name, and installation directory and enter a password for the Postmaster account. You must supply more information if you use a dial-up Internet connection rather than a permanent network connection. After installation completes, you can view the NTMail Release Notes.

I used a Web browser to connect to NTMail on port 8000 and enter the license keys. The product documentation didn't include instructions for entering license keys; luckily, I found these instructions in the email message that contained the license keys.

Documentation. The Lab's review copy of NTMail shipped with two manuals, the Administrator's Guide and the Reference Guide. Both manuals ship in hard-copy and PDF format. The software's retail version will include a user's guide. The Administrator's Guide includes a good introduction to Internet mail concepts, including DNS and the relationships between various mail protocols.

Configuration and management. NTMail doesn't have a standalone administration and configuration utility; you use your Web browser to administer the product. You can use the Web-based administration tools to tune the software for performance. You can set the number of concurrent connections to NTMail for incoming SMTP mail, outgoing SMTP mail, POP client connections, IMAP client connections, and Web mail connections to a maximum of 255. Although this number of connections is certainly adequate for many organizations, the limitation affected my benchmark tests, which required a concurrent connection for each simulated user. However, one simulated user in my benchmark tests generated a much larger mail load than any individual user would generate. Although Gordano says 255 threads is more than sufficient for some very large sites that use NTMail, I suspect that large organizations with POP or IMAP clients that connect every few minutes to check for new mail might find 255 threads limiting.

Gordano supplies the mail.exe utility with NTMail for diagnostic and scripted operations. Some of the utility's functions are meant to be used interactively (e.g., to look up MX records associated with a particular host name). Other functions are intended for scripted or batch operations (e.g., to create a batch of new users from a text file).

NTMail has flexible support using NT accounts for mailbox access authentication. The easiest method is to create a group on the mail server with the same name as the mail domain. The software automatically creates mailboxes for group members. Alternatively, to support multidomain environments, you can create the group on a member server anywhere on the network or on the PDCs of several domains.

POP, IMAP, and Web access. Using POP3 and IMAP4 clients to send, receive, and manage email was easy and unremarkable. I found no surprises in this phase of the testing. I sent and received mail, created IMAP folders, and moved mail between folders.

Web access is the most convenient way to access NTMail. Because Web access requires no special client program or profile, you can retrieve your email from any computer that can provide a network link to the NTMail server. In addition to letting you read and send email, the Web client also lets you edit information that the software returns in response to a Finger request and establish automatic replies to incoming email messages. The software lets you limit the frequency at which the software sends your automatic reply to people who regularly email you once every n days.

However, for reading and sending email—what the majority of users most want to do—NTMail Web access support is a failure. When you want to view a list of your incoming messages, you can see only five messages at a time, and NTMail lists incoming messages in chronological order, forcing you to wade through your older messages before you can read the newer ones. When you finally get to view new messages, all of the SMTP headers display, which makes finding the text portion of the message difficult, particularly if the message is short. You can't resize the portion of the screen that the program dedicates to message display, and the screen is so small that you need to scroll through all the headers to find the message, as Screen 6 shows. The Web interface allows no access to folders—all email messages display in one list. I would use NTMail's Web access mail client only if I were desperate.

List-server features. NTMail includes an integrated list server that is limited to a maximum of 250 members per governed list and a maximum send rate of 5000 messages per hour. For larger lists or faster throughput, you must purchase NTMail's companion product, NTList. NTList is a full-featured product that integrates tightly with NTMail. You can run NTList as a standalone list management server with other mail servers, such as Microsoft Exchange. You administer NTList through the same Web interface that NTMail uses, and NTList supports both moderated and user-selectable digested lists. You can control list access in many ways; for example, you can restrict lists to list members, password-protect lists, and employ wildcard email address restriction. You can also configure list access to be unrestricted or shut down list activity without deleting the list.

Performance. Although NTMail's performance is respectable, its tested throughput, at 34.3tps, is half the throughput rate of the fastest server in this group. Even so, 34.3tps is more throughput capacity than most organizations need.

Final valuation. As a standalone package, NTMail is my least favorite product of the six I tested. If you need licenses beyond 50 users, NTMail is more expensive than better-performing and more fully featured systems. Although the product has a Web client, the client is painful to use. Finally, NTMail's performance-tuning options are more restrictive than those of some of the other servers in this group. I can't recommend NTMail.