Everlasting 5.5?

Even though any form of official support from Microsoft for Exchange 5.5 is long gone, there are still folks using it out in the field.  There are several reasons for this phenomenon, but the most commonly quoted to come across my desk are:

1 - It's working, leave it alone.  Often times, when folks are confronted with upgrading something that's humming along smoothly (from their perspective), they're very hesitant to muck around with it.  While the feature set was much more limited than Exchange 2000 and up, 5.5 did indeed work - insofar as it could host email boxes.

2 - Something else is working, leave it alone.  In many cases, there are 3rd-party systems that the company in question relies on to do their business.  If they never upgraded those applications (possibly something like a billing or accounting system, for example) then they may not be able to upgrade the email systems those 3rd-party systems rely on.

3 - We can't afford to spend millions customizing the new stuff.  This is the big one.  Exchange 5.5 users often had tons of custom forms, API plug-ins, and other customizations made to their servers.  This meant spending tons of cash to contractors and developers to come in and build those customizations if the company in question didn't have that talent-base on staff.  To migrate to a new version (especially 5.5 to anything afterward) would require a total re-write of those customizations, which today could run into some very big bucks.  Many firms simply can't justify the budget.

None of these should be an excuse for not upgrading in the last 8+ years, but all of them are explanations I've personally received when walking into clients who are still on Exchange 5.5.  It many not be dying the dignified death Microsoft had hoped for when they released Exchange 2000 Server oh so long ago...