We now have a PGP/GPG option to always sign outgoing 
messages.  (Yay!)  Now I'd like to have an option which 
turns on *encryption* by default: "Always Encrypt".

With this option on, outgoing messages would always be
encrypted to every recipient for whom a public key is 
available.  If there were any recipients of a message
for whom a PK was NOT available, then a warning/option
dialog would be displayed:

  "WARNING: No public keys available for the following
  message recipients:

    <recipient x>
    <recipient y>
    ... etc.

  What would you like to do?
    o Only send to recipients for whom a PK is available.
    o Send a plaintext version to these recipients.
    o Don't send."