Hello Andrea,
Your account is hosted on a Windows Plesk server and spam filters can be configured from Plesk as well we as in MEwebmail. It will not work by just enabling the spam filters but it needs proper configuration.
HERE is the link for complete information on configuring effective spam filters from Plesk.
To configure it in MEwebmail, following are the steps -
Login your email account in MEwebmail >> at the left pane under "MailEnable - Options" click Filtering >> Add >> here you can add the filter as per your requirement.
Available Filtering Criteria are -
Message From:
Message To:
Message Cc:
Message To or Cc:
Attachments:
Message Subject Contains:
Message Contains:
add appropriate Filtering Criteria, select Action at bottom (Action can be Delete/Move/Copy/Quarantine message) and hit "Add".
Additional setting is available under "Spam Rules" section using which messages are ranked according to rules defined.
I would suggest you to email us at windows [@] eukhost.com if you face any issues while configuring filters in Plesk.