mml-enable-flowed

mml-enable-flowed is a variable defined in `mml.el'.
Its value is

t

Documentation:
If non-nil, enable format=flowed usage when encoding a message.
This is only performed when filling on text/plain with hard
newlines in the text.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.1 of Emacs.