message-use-idna

message-use-idna is a variable defined in `message.el'.
Its value is

nil

Documentation:
Whether to encode non-ASCII in domain names into ASCII according to IDNA.
GNU Libidn, and in particular the elisp package "idna.el" and
the external program "idn", must be installed for this
functionality to work.

You can customize this variable.

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