One nice user has now sent me a sample of those registry keys.
There was a big misunderstunding here.
The basic file extension keys looks like this:
HKEY_CURRENT_USER\.ABC
ZAMailSafeExt=xxx
I thought the problem was that the products were listing the ZAMailSafeExt=xxx registry entries as invalid, but they are not listed as I have tested on my computer.
The problem really was that the entire key (HKEY_CURRENT_USER\.ABC) was listed. I didn't know ZoneAlarm re-creates the entire key if its removed, I thought it only re-creates the entry (ZAMailSafeExt=xxx).
I'm glad that this thing is finally solved, it started to get all too strange.
Anyways, this problem is fixed in the next updated version.