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By Kevin Erickson
[ The opinions expressed by authors on Linux Today are their own. They speak only for themselves and not for Linux Today. ] (lt ed -- The following article is the winner of the grand price for Best Business Case Study in the First Annual Linux Solutions Awards. I work for a growing company of about 1800 employees. Over a year ago we were faced with a decision on an e-mail system for our corporation. At the time, we used Lotus cc:Mail for electronic mail and Lotus Organizer for group scheduling. There were several reasons why we needed to consider a change. First, Lotus had announced that cc:Mail was a dying product, and would be replaced by Lotus Notes. Second, we had fallen behind in some of our upgrades, possibly contributing to the fact that we were experiencing more and more down time, and that users were expressing frustration over the lack of reliability in our cc:Mail system. In addition, the version of cc:Mail that we were using was not Y2K compliant. Third, maintenance, support and upgrade charges continued to grow along with our user base. At this time we began to evaluate several solutions. We looked at Lotus Notes, Microsoft Exchange, Novell GroupWise, and an open system approach based on POP3 and IMAP protocols. End users were accustomed to several features in the current system. We felt we needed to make as many of those features available as possible. Some of them were: ability to store mail on the server; ability to share public "bulletin boards"; centralized address book; public and private mailing lists; ability to use rich text in e-mail; ability to schedule meetings based on other users' schedules; and ability to delegate maintenance of a calendar. Other features we were looking for included high uptime and reliability, the ability to scale to our growing user base, and the ability to recover deleted mail or recover from a failure. Ease of conversion from the old system, and end user training were also factors. End users evaluated front-end applications and determined that Microsoft Outlook had the usability and features that they wanted. IT staff evaluated back end solutions. We determined that we wanted to avoid proprietary architectures, so a solution that at least supported POP3 and IMAP protocols was essential. Integrated SMTP support was also a requirement, eliminating the need for proprietary gateways. I determined that for a fraction of the cost, we could implement an open solution based on Linux that would have 85% to 90% of the features of the other solutions. Going forward with my recommendation, we entered into a pilot phase. The pilot was implemented for a small group using Outlook97 accessing a small Linux server. The pilot, for the most part, was a success. We went through some growing pains as we expanded the usage of the system, leading us to the configuration we have today. Our main mail server today is a Compaq Proliant 1600R, Pentium II 450MHz, with 256Meg RAM, with a DPT RAID controller managing a 16Gig RAID5 volume. The server is running Red Hat Linux 5.2, and services between 1500 and 1700 users. The primary software products used in the solution are:
Client desktops range from Pentium 100 to Pentium II 400, and are all running Windows95 or Windows NT Workstation using Microsoft Outlook 98 in an "Internet Only" configuration. The clients are also equipped with Microsoft Internet Explorer 4. I'll describe the features of my solution, and how each software product is configured to meet each requirement. The ability to store mail on and retrieve mail from the server is provided by the Cyrus IMAP server. Outlook98 supports access to that mail via IMAP and POP3 accounts set up in Outlook 98. The IMAP account also allows access to shared IMAP folders set up with Cyrus IMAP and used as a bulletin board for sharing information with many other users. The Outlook98 client supports e-mail in HTML format allowing for rich text to be embedded in messages. To allow for a centralized address book, I implemented the OpenLDAP server. It is populated with our corporate directory, and provides such information about employees as email address, phone number, employee number, department number, division, department, building, and other internal information. With the LDAP support in the Internet-Only version of Outlook98, a client can type a name or partial name, resulting in an LDAP query that returns that person's e-mail address. In addition, I wrote a Perl/CGI-based web interface to the LDAP directory, which has replaced the monthly printing of hundreds of internal telephone books. A user can search by name, phone number, or any other field, resulting in a full display of user information including a JPEG photo. The Addressbook within Outlook 98 supports private mailing lists. Public mailing lists are supported the Smartlist mail processor based on Perl and Procmail. Users can subscribe or unsubscribe from mailing lists via e-mail. In addition, lists are generated based on department, division, etc from the LDAP server and placed in Smartlists. Group scheduling is supported by the integration of vcalendar support in Outlook 98. I set up an anonymous FTP server using WU-FTPD, which allows for the publishing of free/busy times (vcalendar files) to the FTP server. An Apache server on the machine hosts a virtual web site, which serves up those same files. As changes are made to the Outlook 98 calendar, the information is automatically published to a specified URL, in my case, the address of the anonymous FTP server. When a user wants to schedule a meeting with someone, they type the name into a meeting request, an LDAP query is automatically done, and the resulting information is used to access the users free/busy vcalendar information via an HTTP URL pointing to the same location. This feature makes scheduling a meeting with many people very easy. Delegation of calendar maintenance was a feature required by those management personnel with secretaries. My solution supports this requirement using a feature of Outlook 98 called Net Folders. This feature basically allows one to share your calendar (or any other folder, e.g., Contacts) with other users via e-mail. As updates are done to the shared folder, e-mails are generated that automatically populate that folder on the recipients' client. Uptime and reliability for the solution has been excellent. The current uptime for the main server is 152 days, with downtime being caused by the need to tune various parameters to support the growing user base. We are using IBM's Adstar Distributed Storage Manager (ADSM) for backup and recovery. This allows us to easily recover individual e-mails that users may inadvertently delete, and positions us to easily recover the system in the event of a disaster. There are several other features currently being planned or partially implemented. Since the Cyrus IMAP server does not require a Unix account to be created, one of our sites has been converted to use PAM_LDAP so that authentication of the account is done via LDAP to the OpenLDAP server rather than to the /etc/passwd file. This allows for centralized usercode / password administration across several mail servers and the elimination of the need for root access to the mail server for account administration. We also plan to modify our Sendmail configuration so that incoming mail will generate an LDAP query to find the location of a user mailbox, eliminating the need for a separately maintained Sendmail alias file. Another feature to be investigated is integration of mailing lists via the LDAP mailgroup object. In conclusion, our Linux-based solution for e-mail has been a tremendous success. It is difficult to determine an exact dollar figure saved compared to the other solutions considered. The amount saved on client licenses alone has more than paid for our solution. We are distributing mail servers based on this configuration to all of our offices throughout the U.S., and are continually looking for ways to improve.  
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