On 2 Oct 2018, at 15.28, Jerry <jerry@seibercom.net> wrote:

Nobody is going to stop using Outlook because some *.nix user has gotten his
shorts up in a knot. Now, I did ask this question on a MS Outlook Tech Forum.
One of the first responses I got was to ask exactly what Dovecot's response
was to the attempt to create this folder; i.e., what error message or code
was returned by Dovecot. I don't have the answer to that. If someone can
supply me with the complete and accurate return code I will post that and see
what transpires.