[NEWBIE] Espionage interfering with Apple Mail?

[z80al]

A couple of days ago, I downloaded and installed a trial of the latest version of Espionage on my Mac, running OS X 10.6.8.
To trial it, I copied a folder containing miscellaneous Word and Excel files to an (empty) external USB flash drive, then encrypted that folder (on the external drive) using Espionage, for which, incidentally, I had set the Master Password as being the same as my Mac administrator password.
Espionage appeared to work as advertised but, shortly after its (Espionage's) installation, my mail program (the standard Apple Mail) began demanding my admin password on a regular basis.
I immediately uninstalled Espionage, and Mail immediately reverted to its normal behaviour i.e. it no longer kept asking for the admin password.
The only encryption I had done with Espionage was the one folder on the external USB drive, and there were definitely no Mail-related files in that folder - just Word and Excel files. Nothing on the main Mac disk was Espionage-encrypted - in fact, I very deliberately confined Espionage operation to the external flash drive while i was testing the program.
I would still like to buy and implement Espionage, but I'm nervous about this anomaly by which Mail apparently(?) decided to regularly start requiring an admin password in order to function. It had never done so before, yet it started doing it when Espionage was installed, and it stopped as soon as Espionage was uninstalled - I can only conclude that this was definitely Espionage-related(?)
Am I missing the point? Does Espionage interact with Mail operation in some way? Can anyone advise?

[zsolt]

This post is handled as support ticket too, I will post the result once we figure out what happened.
Cheers
Zsolt