WINDOW LIVE MAIL
Version 2012 (Build 16.4.3528.0331)

The message could not be sent.

Type an email address for one or more recipients in the
To: Cc: or Bcc: box.

Most always this
Error message using win8.1-64

Irritating work-around solution
(to a feature offered as "working") =
save message w/o recipients
close down WLM at least once/twice/more
then try, try  again ?!?!?!?

Other than recreating a group "Category", no other changes nor solutions seems to work as well as this recreation!

MS = The best & richest in OS development?