Step1: In the management area of the Plesk home screen, click Email Addresses to go to the Mail page.
Step2: On the Mail page, click the email address to be protected with spam filters.
Step3: On the email account page, click the Spam Filter tab.
Step4: Uncheck the box Switch on spam filtering for this email address to turn on spam filtering.
Step5: Click OK to save your settings and return to the Mail page or click Apply to save your settings and return to the General tab for the user.