Spam filtering helps keep inboxes usable and reduces the risk of malicious links or attachments. Plesk includes a built-in spam filter that can be enabled per mailbox and tuned to match how strict you want filtering to be.
This feature is commonly used on environments managed through Plesk hosting where email settings are controlled at the domain level.
How the Spam Filter Works
When the spam filter is enabled, incoming messages are analyzed and given a score based on multiple characteristics. Depending on the score and your chosen action, messages can be marked, moved to a spam folder, or deleted.
You can adjust sensitivity and maintain trusted and blocked sender lists to improve accuracy over time.
Enabling the Spam Filter
Step 1: Open the mailbox settings
Log in to the Plesk control panel.
From the main screen, open Mail and click the email address you want to protect.
[Screenshot: Mail page with selected mailbox]
Step 2: Turn on spam filtering
Open the Spam Filter tab.
Enable Switch on spam filtering for this email address.
Choose what should happen to messages classified as spam:
- Mark messages by adding text to the subject or body
- Move messages to the Junk or Spam folder
- Delete messages automatically
Moving spam to a folder is usually recommended so messages can be reviewed if needed.
Click OK or Apply to save the settings.
[Screenshot: Spam Filter tab with options enabled]
Advanced Spam Filter Settings
For more control, open Advanced Settings on the Spam Filter tab.
Adjusting sensitivity
Use the Spam filter sensitivity setting to control how aggressively messages are classified. Higher values catch more spam but may increase false positives.
Managing trusted and blocked senders
- White list allows domains or addresses that should always be accepted
- Black list blocks known spam senders permanently
These lists help fine-tune filtering without relying only on scoring.
[Screenshot: Advanced spam filter settings]
Save the changes once adjustments are complete.
Disabling the Spam Filter
If legitimate messages are not arriving, the spam filter can be temporarily disabled.
Open the mailbox, go to the Spam Filter tab, and clear Switch on spam filtering for this email address.
Save the change and ask the sender to resend the message.
Practical Notes
- Review spam folders regularly to avoid missing important mail
- Avoid setting sensitivity too high initially
- Do not use automatic deletion unless you are confident in the configuration
For higher accuracy and centralized filtering across multiple domains, the built-in filter is often combined with services like Spam Experts, especially on mail systems hosted on cloud servers.