Enabling a Spam Filter in Plesk

Spam emails can clutter your inbox, slow down your productivity, and even pose security risks. If you’re hosting email accounts on a Plesk server, SpamAssassin is a powerful tool that can help you filter out junk mail effectively.

In this step-by-step guide, we’ll show you how to enable, configure, and troubleshoot SpamAssassin on both Windows and Linux Plesk servers.

What is SpamAssassin?

SpamAssassin is an open-source spam filtering tool that analyzes incoming emails and assigns them a spam score based on different criteria, such as:

✅ Blacklisted senders
✅ Suspicious email patterns
✅ Keywords and known spam phrases
✅ Header analysis

If an email exceeds the spam threshold, SpamAssassin marks it as spam, and depending on your configuration, it can be filtered into a junk folder or deleted.

📌 Why Use SpamAssassin on Your Plesk Server?

✔ Reduces spam – Blocks unwanted emails automatically.
✔ Protects against phishing & malware – Identifies dangerous messages before they reach users.
✔ Saves storage & bandwidth – Prevents unnecessary emails from clogging your inbox.
✔ Customizable settings – Adjust spam filtering rules for better accuracy.

How to Enable SpamAssassin on Plesk (Windows & Linux)

Enabling SpamAssassin on Plesk for Windows

🖥 Follow these steps to activate SpamAssassin on your Windows Plesk server:

1️⃣ Log in to Plesk

• Open your Plesk Control Panel and enter your admin credentials.

2️⃣ Navigate to Spam Filter Settings

• In the left menu, go to Tools & Settings.
• Under the Email section, click Spam Filter.

3️⃣ Enable SpamAssassin

• Check the box for Enable server-wide SpamAssassin filter.
• (Optional) If you want mailbox users to configure their own spam filter settings, check Apply individual spam filter settings.

4️⃣ Customize Spam Filtering Options

• Adjust the spam threshold score (lower values block more spam).
• Add whitelisted and blacklisted email addresses.
• Choose how spam emails should be handled (move to spam folder, delete, etc.).

5️⃣ Save Settings

• Click OK to apply the changes.

Enabling SpamAssassin on Plesk for Linux

📌 If your Plesk server runs on Linux, you may need to install SpamAssassin first.

1️⃣ Log in to Plesk

• Open your Plesk Control Panel.

2️⃣ Install SpamAssassin

• Click Tools & Settings in the left menu.
• Under the Plesk section, select Updates.
• In the Install Plesk or Upgrade window, choose Add/Remove Components.
• Expand the Mail Hosting section.
• Locate SpamAssassin, click the down arrow, and select Install.
• Click Continue and wait for the installation to finish.

3️⃣ Enable Spam Filtering

• Return to Tools & Settings → Spam Filter.
• In the Settings tab, check Enable server-wide SpamAssassin filter.
• (Optional) Check Apply individual spam filter settings to allow mailbox users to configure their own settings.

4️⃣ Adjust SpamAssassin Settings

• Set the spam threshold score.
• Configure how spam messages are handled.

5️⃣ Save Changes

• Click OK to enable SpamAssassin.

Troubleshooting Common SpamAssassin Issues

Even though SpamAssassin is effective, you might encounter some issues. Here’s how to resolve them:

1️⃣ SpamAssassin Is Not Filtering Emails Properly

Possible Causes:

• The spam threshold is set too high (spam emails are not being caught).
• The service is not running.
• The SpamAssassin database is outdated.

Fix:

• Lower the spam threshold score (try 5.0 or lower).
• Restart SpamAssassin:
  
  bash

  CopyEdit

  service spamassassin restart

• Update SpamAssassin rules:
  
  bash

  CopyEdit

  sa-update && service spamassassin restart


2️⃣ Plesk Mailboxes Still Receiving Spam Emails

Possible Causes:

• SpamAssassin is enabled but not actively processing emails.
• DNS blacklists (RBLs) are not being used.

Fix:

• Check if SpamAssassin is running:
  
  bash

  CopyEdit

  service spamassassin status

• Enable DNS blacklists in Spam Filter Settings.

3️⃣ SpamAssassin Is Marking Too Many Legitimate Emails as Spam

Possible Causes:

• The spam score is too low, marking normal emails as spam.
• Important email senders are not whitelisted.

Fix:

• Increase the spam score threshold (e.g., 7.0 or higher).
• Add trusted senders to the whitelist in SpamAssassin settings.

Final Thoughts: A Cleaner Inbox with SpamAssassin

By enabling SpamAssassin in Plesk, you can significantly reduce spam emails, improve security, and ensure a better email experience for your users. Whether you’re running a Windows or Linux server, configuring SpamAssassin is a quick and effective way to block junk mail before it reaches inboxes.

🚀 Try these steps today and take control of your email security!

💬 Have you used SpamAssassin in Plesk? Share your experience or ask any questions in the comments below!