Quick Summary: Sudden spike in spam? Learn why hitting "Delete" actually stops your filter from learning, how to train SpamAssassin Bayesian filtering, and what steps to take when facing aggressive spam surges.

The Science Behind the Filter: What is SpamAssassin Bayesian?

Your Rebel Plesk hosting server uses an enterprise-grade security engine called SpamAssassin. Inside this engine is a smart, learning artificial intelligence called a Bayesian Filter.

Think of the Bayesian filter like a digital security guard that needs to be trained:

• It analyzes the mathematical probability of words, links, and server headers inside your emails.

• When you tell it what spam looks like, it memorizes those specific "fingerprints."

• Over time, it gets smarter and automatically blocks similar messages at the server gateway before they ever touch your inbox.

The One Mistake Most Users Make: The "Trash" Trap

When a sudden surge of spam hits your inbox, your natural instinct is to check the boxes and hit Delete to clean up your workspace.

Why this hurts your security:

Moving a spam message straight to the Trash folder tells the server, "I am done reading this email." It does not train the filter.

Even worse, emptying your Trash completely destroys the raw email headers, preventing our senior engineers from finding the spammers' rotated IP networks if you ever need to escalate a ticket.

What to Do During Aggressive Spam Surges (Back-to-Back Emails)

While Bayesian learning builds over time, spammers frequently rotate domain names, relay servers, and IP ranges specifically to bypass score-based filters. If you receive sudden clusters of spam (e.g., 8–12 messages in a row), moving them to Junk alone may feel slow.

How to Request Server-Level Firewall Blocks:

When filter training isn't stopping an active spam campaign, our Senior Systems Engineers can deploy hard firewall/subnet blocks at the server gateway. To do this, support needs raw email headers to trace the originating spam servers:

1. Download 3 to 5 .EML Files: From your webmail or desktop email application, drag and drop 3 to 5 recent spam emails onto your desktop to save them as .EML files.

   • Need help exporting files? Follow our step-by-step guide: Rebel Plesk Email: How to Download a .EML File in Webmail.

2. Attach Files to Your Ticket: Reply directly to your support ticket and attach those .EML files.

3. Leave Live Samples in Junk: Leave a few unread spam samples sitting live inside your Junk/Spam folder so administrators can inspect live server routing if needed.

The Essential Do's and Don'ts for Plesk Users

WHAT TO DO:

• Move Spam to the "Junk" or "Spam" Folder: When an unwanted email slips into your Inbox, explicitly move it to your designated Junk or Spam folder. This simple action triggers the Bayesian engine to scan the message and actively train itself to block future variants.

• Verify Mail Server Settings: Ensure your email software (Outlook, Apple Mail) connects to mail.yourdomain.com over SSL to prevent antivirus software (like Bitdefender) from triggering false security alerts.

• Leave Samples Live for Support: Keep a batch of recent spam messages sitting live in your Junk folder when opening an escalation ticket.

WHAT NOT TO DO:

• Do Not Just Hit Delete: Avoid moving active spam straight to the Trash folder.

• Do Not Unsubscribe From Malicious Spam: If the email looks dangerous, fake, or highly aggressive, never click the "Unsubscribe" link. Doing so confirms to spammers that your email address is active and monitored, which will instantly double your spam volume.

Step-by-Step: How to Boost Your SpamAssassin Scoring in Plesk

If you want to make your email filter more aggressive right now, you can adjust your threshold settings directly inside your control panel:

1. Log into your Plesk Hosting Dashboard.

2. Navigate to Mail > Mail Addresses and click on your email address.

3. Click on the Spam Filter tab.

4. Ensure the checkbox for "Switch on spam filtering for this email address" is active.

5. Click Advanced Settings to expand options.

6. Adjust the Spam Filter Sensitivity (Score):

   • The default score is 7.

   • Lowering the number (e.g., to 5 or 4) makes the filter much more aggressive.

   • Note: Be careful setting it too low (below 4), as it might catch legitimate business emails!

By working together and feeding the Bayesian filter the correct data—or sending us raw .EML headers for server firewall blocks during heavy bursts—we can keep your workspace secure and free of disruptions!