This is a configuration issue, not a bug.

use

mail_home=/path/to/some/directory

mail_location=maildir~/Maildir

that is, make sure the mail location is under mail home (even for
virtual users).

Aki

On 24.01.2018 13:03, Thorsten Hater wrote:
> Hi everyone,
>
> I have noticed recently that Dovecot creates lock directories
> under users' Maildirs which look like IMAP folders. This is bad
> since users will see IMAP folders that are not supposed to be
> there.
>
> In my logs I see
>
> dovecot: imap(...): Error:
> file_create_locked(/.../Maildir/.vsize.lock) failed: Is a directory
>
> The directory in question
>
> # ls /.../Maildir/.vsize.lock/
> cur/
> dovecot.index.log 
> dovecot-uidlist   
> maildirfolder    
> new/              
> tmp/
>
> so Dovecot seems to think this to be an IMAP folder.
>
> I am using Dovecot 2.2.27 under Debian, built from source,
> the lock_method is set to fnctl, and the quota plugin uses the
> maildir method.
>
> Can somebody advice me on how to fix this?
>
> Best regards,
>  Thorsten