Would it be possible to add an option to the contacts, whereby an individual 
could be marked as "preferring" encrypted mail?

When you reply or forward or send a letter to this individual, the "encrypt" 
option will be turned on for that individual. The user should be able to
force it off before sending the letter, if they don't want encryption "this
time". 

Having a similar "Signing" option might not be that bad an idea, also.


It is very probable that you would like to encrypt to everyone in your
contacts, and anyone else who writes you, either. It is far more probable
that there are just a few individuals you would regularly write encrypted 
messages to. Thus, a per-person default would be more useful than a global
encryption default.

murf