Thank you, Han. I am going to move this topic to the Pegasus Mail support forum (which is where it should have been in the first place - sorry!).
I'm looking for a solution that doesn't require user interaction. There's two reasons for this; one: I've trained the users to be suspicious of email that wants to be activated in such a fashion (that training has paid off significantly in the past - we got hundreds of email zip viruses on day zero) and two: my users, my management, and I myself want this sort of thing to be handled in a completely user-transparent fashion. These people do not want to mess about tuning their email system, they want to do their real jobs.
Most of Pegasus's configuration is extremely well suited to this sort of thing; flipping switches from N to Y or editing strings is pretty easy to do on a massive scale, and using INI files means that configurations can be stored and backed up using very OS-agnostic methods. There's no putzing about with registry imports and exports that may or may not be written to disk or held in memory at any given time, there's no relative identifiers encoded into anything. The only exception is the bit-mapped and byte-mapped variables, and even those can generally be decoded by simply turning stuff on and off and diffing the resultant INI files.
For example: If I wanted to set the "organization string" for 10,000 users without having to co-ordinate the efforts of 10,000 human beings, I could do it all by myself with four or five lines of code. Pegasus's simple, clean ASCII configuration is what allows me to do so. Registry-driven software is inherently more difficult and cost-ineffective to manage.