SCOoffice Server 2.0 for UnixWare - Technical White Paper

The UnixWare® Office Mail Server Release 2.0 provides a secure, robust, and easy-to-use e-mail and collaboration server. Based on open standards for e-mail and directory services, UnixWare® Office Mail Server Release 2.0 supports a wide range of popular desktop e-mail clients including Microsoft Outlook®, Netscape Communicator®, and Qualcomm® Eudora.

Revision 3 - January 2, 2003

By Louis D. Imershein
August 27, 2003

The SCO Group
Lindon, UT  USA

Copyright © 2003, The SCO Group, Inc. (“SCO”). All Rights Reserved. No part of this document may be copied or translated to another language without the express written consent of The SCO Group. The SCO documents are provided “as is” and may include technical inaccuracies or typographical errors. The SCO Group reserves the right to add, delete, change, or modify Caldera documents at any time without notice. The documents are for information only. SCO makes no express or implied representations or warranties of any kind. Caldera International, The SCO Group, SCO, the SCO logos, SCOx, SCObiz, and TeamSCO, are trademarks or registered trademarks of The SCO Group. UNIX and UnixWare are used under exclusive license, are registered trademarks of The Open Group in the United States and other countries. All other brand and product names are trademarks or registered marks of the respective companies. Specifications subject to change.

Table of Contents
1.     Executive Summary
2.     Introduction
3.     Features of UnixWare® Office Mail Server Release 2.0
4.     Architecture Overview
  4.1   Design Goals
  4.2   Principle Components
    4.2.1 Postfix
    4.2.2 Cyrus IMAP Server
    4.2.3 OpenLDAP Directory Server
    4.2.4 Server Manager
    4.2.5 Server Utilities
    4.2.6 Preferences Manager
5.     SCOoffice Mail Connector
  5.1   SCOoffice Mail Connector for Microsoft Outlook
  5.2   SCOoffice Address Book for Microsoft Outlook
6.     Partner Products
  6.1   Anti-Virus
  6.2   Clustering
  6.3   Backup Products
  6.4   FAX Products
  6.5   Time Management
  6.6   Trust Services
7.     System Requirements


UnixWare® Office Mail Server Release 2.0
Technical White Paper

1.  Executive Summary

The UnixWare® Mail Server Release 2.0 provides a secure, robust, and easy-to-use e-mail and collaboration server. Based on open standards for e-mail and directory services, UnixWare® Office Mail Server Release 2.0 supports a wide range of popular desktop e-mail clients including Microsoft Outlook®, Netscape® Communicator, and Qualcomm® Eudora.

Each copy of the UnixWare® Office Mail Server includes a copy of SCO UnixWare® 7.1.3. UnixWare® Office Mail Server Release 2.0 is designed to integrate with a wide range of third-party messaging products that provide backup, fax, and virus detection services.

This document is meant to provide a high-level technical overview of the UnixWare® Office Mail Server Release 2.0. For additional information, contact your SCO reseller or visit our website at

2.  Introduction

UnixWare® Office Mail Server Release 2.0 is a server-based e-mail and collaboration platform. E-mail and collaboration products are especially beneficial in situations that require solid communication between individuals, as well as those requiring communications with electronic information services. UnixWare® Office Mail Server Release 2.0 takes advantage of the wide availability of mail clients and web browsers that allow access to information at any time from anywhere, even under conditions of intermittent connectivity.

UnixWare® Office Mail Server Release 2.0 provides a reliable, robust e-mail and collaboration solution. It offers a lower cost of ownership than the competition through fast installation, minimal training requirements, high reliability and ease of administration. The product is designed so that non-technical personnel can perform day-to-day administration tasks. Opportunities for value added development and integration with existing applications are offered within the architecture of the UnixWare® Office Mail Server, which is both extensible and modular.

UnixWare® Mail Server Release 2.0 is an excellent choice for resellers that service customers with Microsoft Outlook compatible e-mail and collaboration system. UnixWare® Office Mail Server products provide resellers, solution providers, and onsite administrators with a highly available, easily managed, and lower cost alternative to products such as Microsoft Exchange®.

It is when the UnixWare® Office Mail Server is used with the SCOoffice Mail Connector the Mail Server truly becomes a low cost alternative to Microsoft Exchange. For the Outlook end-user, the experience is nearly identical.

3.  Features of UnixWare® Office Mail Server Release 2.0
Feature Description How to use it
User-friendly Installation Utility The Office Mail Server is easily installed via a graphical interface. On UnixWare, mount the CD-ROM, enter the LKP environment, and run the command.
Single-Click Outlook Configuration Configuration of Outlook requires a one-click setup via the Web interface. All that is required is a username and password. No manual configuration of IMAP is necessary. A Volution menu bar link is added to Outlook as part of this process, allowing quick access to Office Mail Server preferences. Users login to the Preferences Manager by pointing their web browsers to the URL, http://server_name/msg (where server_name is the name of the server hosting Office Mail Server) and providing a login and password provided by the administrator. Once the users have logged in, they select Preferences->Client Setup and click the “Configure” button. Users then follow the standard Microsoft Windows prompts selecting to Open the configuration program. Depending on the version of Microsoft Windows® and Microsoft Outlook®, Microsoft Windows® may reboot as part of the configuration process.
Calendaring The Office Mail Server supports ical calendaring, the standard for Internet calendaring supported by Microsoft and many other e-mail client vendors. “Free-busy” information for user calendars is stored on a central server, which can be accessed via FTP or WebDAV services. This allows Outlook users to use Office Mail Server to share calendaring events. This feature is configured automatically as part of the Single-Click Outlook Configuration feature. Users of Outlook versions prior to 2002 also need to modify their password as instructed in the documentation to utilize the “free-busy” component of Calendaring. Once enabled, users can schedule meetings with multiple members and check when a user is busy on the server using the standard Outlook interfaces.
Directory Support User information is stored in the OpenLDAP directory service by Office Mail Server. Administrators manage users through the Web-based management console. Users can access information about other Office Mail Server users either by utilizing the built-in Internet Address Book features of modern e-mail clients such as Microsoft Outlook®, or via the Preferences Manager Users->Find User option.
Integrated UNIX Support Office Mail Server software is bundled with UnixWare® and runs as an LKP application. This allows the Messaging Server to take advantage of the stability and reliability of UNIX. Mount the Office Mail Server CD-ROM and run the command. The installation will automatically tune UnixWare® for Office Mail Server and configure the appropriate services. Once installed, Office Mail Server is managed from within the LKP.
Clustering Support The Messaging Server product supports ReliantHA clustering on UnixWare®, providing additional reliability via fail-over. ReliantHA includes sample startup scripts for cluster-enabling Office Mail Server. See the ReliantHA documentation for more information.
Webmail Users can access their e-mail from anywhere on the Web. Users point their browsers to the URL http://server_name/horde/imp and login with their administrator-provided User ID and password.
Web Management Both administrators and users can manage the system (or their account) with any standard Web browser. No special client training is necessary. Use a Web browser to login to the server through the URL http://server_name/msg . Microsoft Outlook® users can simply click on the SCOoffice menu option once Outlook has been configured.
Built-in Security Office Mail Server is integrated with the OpenSSL package. Secure Internet transport is provided through the SSL and TLS protocols. During installation, the Messaging Server is automatically configured to use self-signed certificates. To use this feature, users simply select to use SSL or TLS within their mail applications.
Junk Mail (SPAM) Filtering Capabilities Office Mail Server provides a set of general spam filter rules that can be applied on a per-user or system-wide basis. In addition, Office Mail Server includes support for the Realtime Blackhole List (RBL).

Junk Mail (SPAM) Filtering Capabilities Office Mail Server provides a set of general spam filter rules that can be applied on a per-user or system-wide basis. In addition, Office Mail Server includes support for the Realtime Blackhole List (RBL). Administrators who subscribe to an RBL service can enter their service address into the file /etc/postfix/ using standard UNIX® tools. This default service is the same as that offered by the non-profit service. Once this step is completed, the administrator simply selects to enable or disable the service via the Web interface.

Users manage their own SPAM filtering rules via the Preferences Manager Preferences->Junk Mail option.

Multi-domain Mail Server Capabilities
The Office Mail Server supports the ability to serve multiple mail domains from a single server. The is useful for service providers or resellers wishing to provide mail services to multiple sites from a single server. Administrators can create and manage domains via the Web-based administration interface. Mail domains must also be managed as MX records in a DNS server that may reside on a different system.
Supports 2,500 simultaneous users
At installation time, Office Mail Server pre-tunes support for up to 2,500 simultaneous users on standard hardware. No action is necessary; this is done automatically at installation.
Dedicated Mail Server The Office Mail Server is designed to act as a standalone dedicated electronic mail server. All account information is stored in a centralized LDAP database. In order to protect the system from local root security exploits, Office Mail Server users do not have system accounts. All Office Mail Server Users can be managed in the LDAP directory via the Web-based management interface, command line tools, or third-party LDAP management interfaces.
Message Filtering
Office Mail Server has the ability to reject mail messages based on header information, message body content, or SMTP envelope information. The server also supports the ability to create server-side rules for depositing content into specific mailboxes. These capabilities can be used to help protect networks from unwanted viruses and junk mail. Message filtering is managed by editing filtering files in the /etc/postfix directory as instructed by the documentation.
Single Instance Message Store
This feature allows e-mail messages sent to multiple users on the same Office Mail Server system to be stored as a single copy, rather than one copy per user. Single Instance Message Store is disabled by default. For help enabling this feature contact your support provider.
Quota Support This feature allows the administrator to enforce the size of the mailboxes allowed on a system. A default quota can be set from the command-line using the msgaclset utility. Once set, all users will be created with that quota. Once a user is created, the administrator can modify a user’s quota using the Web-based management tool via the Users->View Quota link.
International Language support The administration and preferences tools are localized into English, French, German, Italian and Spanish languages. Set the preferred language type in the browser configuration. The proper language files will automatically appear.
Third-party software integration The Office Mail Server is designed to easily integrate with third party anti-SPAM, anti-virus, enterprise calendaring, and fax solutions. See product documentation for details.

4.  Architecture Overview

4.1  Design Goals

UnixWare® Office Mail Server Release 2.0 is a complete Mail Server solution. The design goals of the Mail Server Release 2.0 product required that it be:

  • Easy to install
  • Easy to use
  • Easy of manage
  • Stable
  • Secure
  • Work with popular e-mail clients

SCO achieved these goals by developing easy-to-use management and installation tools and integrating them into a set of open source components built entirely around directory services.

4.2  Principle Components

The principle components of the UnixWare® Office Mail Server Release 2.0 include:

  • Postfix
  • Cyrus
  • Open LDAP
  • Server Manager
  • Server Utilities
  • Preferences Manager

4.2.1  Postfix

The heart of any Mail Server is the Mail Transfer Agent (MTA). This component is responsible for queuing and routing e-mail messages, handling mailing lists and aliases, and forwarding e-mail. Postfix is the MTA used by the UnixWare® Office Mail Server Release 2.0. Unlike other MTA systems, Postfix (originally known as IBM Secure Mailer) was designed explicitly with security in mind. SCO's engineering team has specially configured Postfix to query the LDAP server for information needed to deliver mail, resolve mail addresses, and offer SSL and TLS support.

4.2.2  Cyrus IMAP Server

Cyrus is used to store mail folders. The Cyrus message store provides access to personal e-mail through the Internet Message Access Protocol (IMAP4) and Post Office Protocol (POP). IMAP and POP server are key components that allow e-mail clients to connect to the server and fetchmail. The Cyrus server differs from other message store and IMAP server implementations in that it runs on "sealed" servers, where users are not normally permitted to login. When a user connects to the Cyrus server, the server queries the LDAP directory for authentication of users using the pam_ldap interface provided in the LKP environment on UnixWare®.

The Cyrus message store is stored in parts of the file system that are private to the Cyrus system. All user access to mail is supported through clients using the IMAP and POP3 protocols. The Cyrus mailbox format provides a message store that is much more scalable than the traditional flat file format. The fetchmail utility is available to retrieve mail stored in traditional UNIX flat file mailbox format.

SCO has specially modified the Cyrus IMAP server to provide improved scalability through additional locking and coherency features. SCO has also tuned Cyrus to optimize performance for up to 2500 simultaneous IMAP connections.

4.2.3  OpenLDAP Directory Server

The UnixWare® Office Mail Server Release 2.0 uses a Lightweight Directory Access Protocol (LDAP) directory to store information concerning mail accounts, mail aliases, and the mail domains configured on a server. OpenLDAP is the directory server for Mail Server Release 2.0. Both personal and corporate user information and e-mail authentication data are stored in the directory and easily managed using the Office Mail Server's “Server Manager” utility.

The LDAP directory is an object-oriented database, where virtual objects representing physical objects are stored hierarchically. Relationships between virtual objects govern the behavior and configuration of the physical systems the objects represent. By creating or changing the relationship of a virtual object in the directory, it is possible to change the physical systems’ behavior or configuration.

A directory is a powerful data repository for the UnixWare® Office Mail Server because it identifies every resource and how each relates to other resources. A directory can also be extended to include new types of resources, to modify existing resources, or to add additional attributes to describe them.

4.2.4  Server Manager

The Server Manager is the principal UnixWare® Office Mail Server administrative utility. It is a Web-based management interface, built with the PHP scripting language. The Server Manager provides support for all functions required to administer an office Mail Server on a day-to-day basis. The Server Manager provides functionality to:

  • Add/delete/modify virtual hosts, mail users, and mail aliases
  • Monitor mail services
  • Control client user privileges

The Server Manager provides Mail Server administration screens only accessible by the “admin” administrative user account. By default the Server Manager is served by the Apache Web server at: https://hostname/msg.

4.2.5  Server Utilities

All modifications done by the Server Manager or Preferences Manager are routed through the Server Utilities. These are a suite of utilities, some binary and some Perl scripts, that perform the actual work of day-to-day administration tasks. Perl based utilities can be modified to add extra site-specific features. For example, a simple modification to the msgusercreate utility could be used to enforce a disk quota limit or make sure that a user is also added to a non-LDAP aware application. Additionally, the Server Utilities provide some functionality not offered by the Server Manager. For example, the msgvscan utility can integrate third-party virus scanners with UnixWare® Office Mail Server Release 2.0.

4.2.6  Preferences Manager

The Preferences Manager is the end-user equivalent of the Server Manager. From the Preferences Manager Web page users can login with their mail user ID and password to:

  • Obtain information about mail client settings
  • Configure Microsoft Outlook
  • Manage their address book information
  • Setup forwarding to another account
  • Set a vacation mail notice
  • Change their e-mail user password
  • Locate information about other e-mail users<
  • Manage and share mailing lists

As with the Server Manager, the Preferences Manager is accessed from the URL https://hostname/msg

Microsoft Outlook users can take advantage of the one-click Microsoft Outlook configuration tool provided as part of the Preferences Manager interface. At the press of a button, the client is automatically configured for mail, calendaring, and address book features of the UnixWare® Office Mail Server.

By selecting this option, a Windows Scripting Host (WSH) configuration script is generated on the fly by the msggenclientconfig utility. This script is used to configure Outlook and to download an additional COM add-in that adds access to the Preferences Manager as an option from the Microsoft Outlook menus.

5.  SCOoffice Mail Connector

The SCOoffice Mail Connector contains two components, the Mail Connector itself and the SCOoffice Address Book which is described in section 5.2.

5.1  SCOoffice Mail Connector for Microsoft Outlook

The Mail Connector is an Exchange Client Extension* that enables any version of Microsoft Outlook from 97 through 2002 to change its message, calendar, contact and other stores from Exchange to an Internet Mail Access Protocol service.. Outlook 98 and Outlook 2000 must be configured in Corporate Workgroup mode so that the necessary services of Outlook will be installed and enabled. Outlook 97 and Outlook 2002 have no concept of the Corporate Workgroup mode and provide the necessary services by default.

With SCO’s solution, the Connector provides complete mapping and synchronization of the user’s mail and special folders to the Cyrus IMAP server using the IMAP protocol. MAPI is not used. While this is nothing new for standard mail folders this is very significant in regard to the sharing of the special folders such as calendar, contacts, journal, notes, and tasks. The sharing of the special folders marks the introduction of meaningful collaboration with Outlook on an IMAP based messaging platform. The collaborative features of Outlook that were once available only with Exchange are now a reality without Exchange.

The Connector adds a toolbar of five buttons to the Outlook menu which allows the user to configure e-mail accounts, set folder synchronization options, share folders and set folder access permissions. Aside form this toolbar the user experience of using Outlook with the Connector is essentially unchanged from that of Outlook with Exchange.

Connector toolbar buttons:

  1. IMAP Mailboxes - Configure e-mail accounts and local storage (PST) files. Existing PST files can be used or a new PST file can be created. Profiles, mail accounts and Personal Storage Files can also be managed using the standard Outlook and Windows Control Panel menus.
  2. Mailbox - Specify the IMAP server and IMAP account logon information to which the Outlook e-mail account mail folders are synchronized.
  3. Folders - Allows the user to set up 4 modes of folder synchronization. It also allows the user to share folders by granting specific access rights to specific users or all users. Connector folder permissions are synonymous with IMAP ACL’s.
  4. Synchronize - When pressed, this button synchronizes the selected folder in Outlooks PST file (local message store) with the corresponding folder on the IMAP server.
  5. About - Provides Connector version and company information.

With UnixWare® Office Mail Server and the SCOoffice Mail Connector combined users can collaborate seamlessly. Following are some examples of collaboration:

  • Shared public and private folders
  • Shared special folders - Contacts, Journals, Notes, Tasks, etc.
  • Fine grained user access controls
  • Shared global address lists
  • Shared Calendars
  • Delegate calendar administration
  • Direct booking of resources
  • Private Discussion Groups

5.2  SCOoffice Address Book for Microsoft Outlook

The SCOoffice Mail Connector includes an additional Outlook extension called the SCOoffice Address Book. This feature provides seamless Outlook address list integration and a persistent address list display which allows the user to scroll through address book contents without having to perform a search. Further, it provides increased address book search performance, customizable sorting, and customizable address list search criteria based on LDAP attributes. The result is usability superior to native Outlook LDAP address books.

Like the Connector, the Address Book is compatible with all versions of Microsoft Outlook. Since the Address Book is a MAPI service provider Outlook 98 and Outlook 2000 are required to be configured in Corporate Workgroup mode so that the necessary services of Outlook will be installed and enabled. Outlook 97 and Outlook 2002 have no concept of the Corporate Workgroup mode and provide the necessary services by default.

6.  Partner Products

6.1  Anti-Virus

The UnixWare® Office Mail Server Release 2.0 supports anti-virus products from Sophos ( and Computer Associates ( out of the box. Other products may require additional configuration.

6.2  Clustering

SCO provides the Reliant® HA clustering solution for UnixWare®. The latest version of ReliantHA comes with sample scripts and macros that can be used to configure a clustered Mail Server environment. ReliantHA allows the creation of high-availability clusters of 2-4 nodes, with all nodes simultaneously active. The product supports automated fault detection and recovery with standard Intel-based servers and off-the-shelf RAID and networking solutions.

Additional information on Reliant/HA can be found at:

6.3  Backup Products

The UnixWare® Office Mail Server Release 2.0 supports a wide range of backup software solutions including:

These products offer many competitive features. SCO recommends that you examine them closely to determine which solution is the right one for your application.

6.4  FAX Products

Faximum Software's Faximum Messaging Server is specifically designed to integrate with the UnixWare® Office Mail Server. For additional details on this product see the Faximum website at:

Esker's VSI-Fax product is another fax product that is compatible with the UnixWare® Office Mail Server. Information of VSI fax can be found at:

6.5  Time Management

UnixWare® Office Mail Server Release 2.0 works seamlessly with time management solutions, including the Steltor CorporateTime Server and CorporateTime Outlook Connector products recently acquired by Oracle.

6.6  Trust Services

UnixWare® Office Mail Server Release 2.0 has been tested with SSL Webserver certificates issued by Thawte ( Certificates that are compatible with the Apache Web server will generally function with Mail Server Release 2.0.

7.  System Requirements

Supported Operating Platforms:

  • 10 User UnixWare® Office Mail Edition includes the UnixWare® Base Edition and supports up to 1Gb of RAM
  • 100 User UnixWare® Office Mail Edition includes the UnixWare® Business Edition and supports up to 4Gb of RAM

RAM: Minimum 64MB system + 1MB per connected user, 512MB recommended (in addition to platform requirements)

Processor: A single 2Ghz CPU is adequate for servicing up to 5,000 simultaneous user accounts

Disk Space: Minimum 40MB system + appropriate mailbox allocation per user (in addition to platform requirements)

Networking: TCP/IP Networking with DNS name resolution configured

Installation Profile: UnixWare 7.1.3 + LKP + Web Server profile