mm-decrypt-option

mm-decrypt-option is a variable defined in `mm-decode.el'.
Its value is

nil

Documentation:
Option of decrypting encrypted parts.
`never', not decrypt; `always', always decrypt;
`known', only decrypt known protocols. Otherwise, ask user.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 22.1 of Emacs.