dovecot - Jun 2018 - can't login to Dovecot

I've managed to turn on "plain" and now it seems I can logon.

Jun 13 17:24:20 ulmke2 dovecot[1973]:
imap(ulw)<2474><+kyqk4du5M7AqGQd>:
Namespace '': Mail storage autodetection failed with home=/u/ulw in=0 
out=373 deleted=0 expunged=0 trashed=0 hdr_count=0 hdr_bytes=0 
body_count=0 body_bytes=0
Jun 13 17:24:20 ulmke2 dovecot[1973]: imap-login: Login: user=<ulw>, 
method=PLAIN, rip=192.168.100.29, lip=192.168.100.2, mpid=2476, 
session=<GJCrk4du5s7AqGQd>
Jun 13 17:24:20 ulmke2 dovecot[1973]:
imap(ulw)<2476><GJCrk4du5s7AqGQd>:
Error: Namespace '': Mail storage autodetection failed with home=/u/ulw


All users mailboxes are $HOME/Mail

How do I tell Dovecot this?

-- 
  --
Best Regards, Walter Ulmke

Ulmke Machine Tools,   48496 Hopsten,   Germany
Tel. ++49/5458/93345-0  Fax. ++49/5458/93345-45
Mobile: ++49/172/5357999   eMail: ulw at ulmke.com
Dipl.-Ing. Walter Ulmke e.K. AG Steinfurt HRA 4384

> On 13 June 2018 at 18:31 Walter Ulmke <ulw at ulmke.com> wrote:
> 
> 
> 
> I've managed to turn on "plain" and now it seems I can logon.
> 
> Jun 13 17:24:20 ulmke2 dovecot[1973]:
imap(ulw)<2474><+kyqk4du5M7AqGQd>:
> Namespace '': Mail storage autodetection failed with home=/u/ulw
in=0
> out=373 deleted=0 expunged=0 trashed=0 hdr_count=0 hdr_bytes=0 
> body_count=0 body_bytes=0
> Jun 13 17:24:20 ulmke2 dovecot[1973]: imap-login: Login: user=<ulw>, 
> method=PLAIN, rip=192.168.100.29, lip=192.168.100.2, mpid=2476, 
> session=<GJCrk4du5s7AqGQd>
> Jun 13 17:24:20 ulmke2 dovecot[1973]:
imap(ulw)<2476><GJCrk4du5s7AqGQd>:
> Error: Namespace '': Mail storage autodetection failed with
home=/u/ulw
> 
> 
> All users mailboxes are $HOME/Mail
> 
> How do I tell Dovecot this?
> 
> -- 
mail_location = maildir:~/Mail # or whatever driver you use

Aki