Forward the e-mail with full header information and the body part by opening a support ticket via https://itsupport.metu.edu.tr in order to have the e-mail be defined as spam to the spam filter. You can get information about how to view the full header of a message from this link.

If you are using Horde, mark the spam e-mails and click Report as Spam in order to define them as spam to spam filter.

With the help of the feedback from users, spam filter will be able to differentiate spam messages more effectively.