Move spam to the Spam folder isn't working

Hey guys,

I registered to this forum because I've a problem with the Plesk feature "Move spam to the Spam folder" for each mail address and I couldn't find a solution so far.

Plesk Version: 12.5.30 Update #15
Imap/POP3 Server: Dovecot

Description of my problem:

I enable the Spam filter for any mail address with the checkbox "Switch on spam filtering for this e-mail address" and select the option "Move spam to the Spam folder". Now, arriving spam mails are correctly...

Move spam to the Spam folder isn't working