Understanding and Replacing Microsoft Exchange

The hardest-to-replace Microsoft server software is the expensive, frustrating Exchange. Here's how IBM and Bynari sent it packing.

Linux by itself provides a formidable set of internet applications for mainframes, which have always needed them. IBM's eServer strategy seemed incomplete without a robust set of internet tools, which it promised to provide to all of its brands. Near the end of calendar year 2000, IBM demonstrated it could host a thousand instances of Linux on a single S/390 mainframe.

Figure 1. One mainframe supports thousands of Linux instances.

Even so, IBM realized that web servers and GNU applications didn't provide a complete value proposition. IBM needed an application that made Linux a host that reached further into mainstream computing. So they made a call on us.

In April 2001, when the sales manager for IBM's zSeries, the new name for the S/390, visited our company, Bynari, Inc., I did not understand his interest. After his visit, I understood it perfectly. Bynari, Inc. became IBM's first Linux Influencer Partner.

E-Mail, the “Killer Application”

Initially, people knew us for making Linux and UNIX clients talk to Microsoft Exchange servers. Looking to broaden our market, I found the “Exchange Replacement HOWTO” by Johnson and Mead (www.bynari.net/whitepapers_howto.html). Using their work as a guide, we built a server for our Linux client and Microsoft Outlook. Our server and its Outlook Configuration Guide caught on with the reseller channel.

We didn't know anyone at IBM when we ported our server code to a Linux instance running on an S/390 Multiprise 3000. Jimmy Lee, then with Equant, provided the resources to see if we could do it. Gary Ernst of Equant configured the S/390 instance of Linux and provided assistance in getting our server to work.

As long as Microsoft Outlook had an Internet Mail Only mode and provided peer-to-peer folder sharing, we had a product that allowed UNIX and Outlook clients to schedule meetings and delegate calendar tasks. Our server scaled nicely, and we mimicked the Exchange global address list (GAL) while providing views of users' free/busy time and a decent administrative interface.

But then Microsoft released Office XP and made major changes in Outlook. Suddenly, our products needed server-side calendaring. We feared the growing appetite of IBM enterprise customers for a low-cost server solution for Outlook might wane. Therefore, we needed peer-to-peer calendar sharing in Outlook's Internet Mail Only mode, or we needed something on the server side.

Forty-Five Days to Create a Solution

With the January 2001 LinuxWorld Conference & Expo approaching, IBM continued marketing our server, somewhat blind to the needs of Outlook XP users. I knew we had to do something and do it fast or lose IBM's trust. At that time, the person who best understood the market problem was Roger Luca of Mainline Information Systems.

Fortunately, Roger and I developed a good working relationship. With Roger at the head of sales and marketing, Mainline became the largest reseller of IBM mainframes. They also were our biggest supporter outside IBM. Roger provided us with hardware resources to help us build server-side calendaring into our product, as well as with people to support us if we ran into hardware-related problems.

Surprising the Development Team

Imagine having completed an exhaustive year of development. You have trips scheduled for the holidays and other plans. Then you get a call on your cell phone; your boss asks you to attend an important meeting. That's what happened in our shop. I could hear the dread in the developers' voices when they answered my call.

We met on November 7, 2001, to see if we could deliver a server-side calendar solution by Christmas. Mainline had several sales pending, and they needed that functionality. Two of my people agreed to work with me to get the solution.

Technology Challenges Not for the Faint of Heart

As the senior developer, I provided the project framework. In theory, a project has a variety of phases and processes. To shorten the project's life, I instituted a three-step approach that called for research, invention and execution. I gave each phase a milestone. So instead of starting with code, we started browsing the Internet and any books we could find.

Following a week of intensive research, we discovered our challenges. We had to figure out how Microsoft's DCE-RFC protocol stored and moved calendar events around. We had to interpret the stored data, provide a format that we could store on an IMAP server and then forward the data to an Outlook client in its familiar schema. We also had to provide access control over those information stores to allow a user to appoint and delegate control over his or her calendar to other users with varying permission levels.

We spent another intense week researching and discovered a consensus. Every expert, newsgroup, Outlook specialist and company that tried said one could not create a Microsoft Outlook calendar store on an IMAP server. Here's how we did it.



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Keylogger's picture

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Exchange is easy to replace

Digital Networking's picture

There isn't anything that exchange can do that open source components can't. I found an article which explains exactly how to replace exchange here http://digitalnetworking.biz/how-tos/how-to-replace-exchange-with-open-s...

good article,thn

greymarkus's picture

These two steps can allow a programmer or a seasoned administrator to create an alternative service provider for Outlook and serve a number of conventional mail clients. Linux mail servers do not discriminate based on the platform one uses. One can use Netscape Mail, Outlook Express, Ximian Evolution, mutt or Pine, to mention a few of the available MUA. celebrex 200 mg

Microsoft Outlook the most stable software????

Wong Seoul's picture

"Microsoft Outlook the most stable software"
I can not disagree more. I am not sure how much email you receive everyday.. My MS Outlook crashes all the time.. I lose my emails all of a sudden.. I do not also use MS Exchange and recommend it..


Just a comment

Jairo's picture

Funny how things are... I've been using Outlook for (at least) 10 years now. Without a single "hard crash" as you say, *never* lost any email, *never* had a reason to change. In the (few) times it began to crash from time to time, the reason always was some other software installation that turned it unstable. But it can happen with any other windows software.
In time: except for the extremely high cost, I use (also for several years now) and recommend MS Exchange Server. Having a good (and simple-tasks-based maintenance) you can run it for years with no complaints.

Zarafa full mapi implementation on Linux

Anonymous's picture

Take a look at the Exchange alternative Zarafa (www.zarafa.com). This product has a native MAPI implementation on your Linux server and even support for advanced Exchange features, like Freebusy times, Global Address Book and full TNEF support.

The best thing of the product is the AJAX based webaccess, which is completely in the Outlook "Look & Feel". See demo.zarafa.com.

Awesome work. Thanks for

Anonymous's picture

Awesome work. Thanks for saving the world. You're definitely earned your success and money.

I am a windows developer and

Anonymous's picture

I am a windows developer and worked primarily on windows. I still support linux and love it. I have just thrown windows out of my home computer (will love to do this at work when time comes). I am more than impressed by this effort. Keep up the good work.

Microsoft is doomed!

Anonymous's picture

I am so happy to see efforts like this. I wish for Microsoft to lose their stronghold in the marketplace as soon as possible because diversity in choice of Operating Systems means better security for everyone. Replacement of Microsoft's product lines, one by one, is a truly wonderful move in this direction.


I must admit to being more im

Outlook Express repair's picture

I must admit to being more impressed for it. I've even recommended it to all my friends.

what a waste of time... So

Anonymous's picture

what a waste of time... So have you kept up with Exchange 2007?

I thought not. This is a pointless excercise... How many programmer for how many
years will it take to keep up with Exchange? It would cost you a couple hundred grand
to keep up and you still couldnt handle it. Programmers arent cheap.

Exchange has competitors but they stink and exchange is cheap.

There's nothing "cheap"

Anonymous's picture

There's nothing "cheap" about Exchange!