Incoming e-mails are already checked for spam on the server. Your own spam filter in the e-mail programme overloads the servers, because each e-mail has to be downloaded completely for checking. Furthermore, these spam filters are insecure, as the filter must be trained or sorts out normal e-mails as spam. Therefore, the built-in spam filter should always be deactivated.

• Click on the “Junk E-mail” button under “Start” in the menu and then on “Junk E-mail Options…”.
• Then select the top radio button “Keine automatische Filterung…” (“No automatic filtering…” ) and click on “OK”.