By Mark Craddock
For anyone that has been involved in either managing, designing, deploying or just using Microsoft Exchange and Outlook, I'm almost certain you would recognise the phrase "Requesting data from Exchange server."
That small dialog box that's pops up just as you are desperate to interact with your email has probably been the seed of many profanities across the world. How many of us have watched to the little grey bar extend its way across the screen, soulfully willing it on to the right hand side of the screen so we can send or receive that critical email?
As an IT Manager responsible in establishing a large hosted Exchange environment, I had unwittingly inflicted this problem on my user base and also suffered with it personally. In desperation, a few months ago, I set out, focussed and determined, to eradicate our particular problem. The results were interesting and highlighted a situation which may be applicable to others caught with the same frustrations.
Before I share the findings with you, let me point out that this only represents a possible resolution to the problem in certain topologies, not a definitive fix. As I'm sure those who have investigated this problem will appreciate, this is an advisory message where certainly "one size fits all." It could probably be the most ambiguous and unhelpful prompt in the world, since its presence could be caused by numerous factors.
However, I hope the following information may at least help solve the issue for one or more of you.
It is important to note that the research on this solution is specifically related to Exchange 2000 and Outlook 2000/2002 clients, where the two are separated by one or more firewalls and TCP/IP is the protocol in use. No tests or research was undertaken into other topologies or 2003 variants, however, the underlying principle may still be valuable and applicable.
Some basic concepts
First the concepts. An essential part of the resolving the problem is a detailed understanding of the services that provides the communication between Outlook, Exchange, Active Directory and the global catalogue servers. This is an extensive subject, much of which is outside the scope of this article. Further detailed information can be found on the Microsoft Web site. However, there is one essential component within these services that we need to focus on, that of DSProxy (Directory Services Proxy).
