Managing Spam Filters

Overview

Spam filters analyze incoming email and separate legitimate messages from unwanted ones. Effective spam management helps keep your inbox productive and protects you from phishing attempts, malware, and scams. Most email services include built-in spam filtering, but you can fine-tune the settings for better results.

How Spam Filters Work

Modern spam filters use multiple techniques to evaluate incoming messages:

• Header analysis — Checks the sending server’s IP, SPF/DKIM/DMARC results, and message routing.
• Content analysis — Scans the subject line and body for spam trigger words, suspicious links, and patterns.
• Reputation scoring — Evaluates the sender’s domain and IP reputation based on historical data.
• Bayesian filtering — Learns from messages you mark as spam or “not spam” to improve accuracy over time.
• Blocklists and allowlists — Compares senders against known spam sources and trusted sender lists.

Configuring Spam Filters in cPanel (SpamAssassin)

Most hosting plans from 10Corp use Apache SpamAssassin, which scores each message. Messages above a threshold are marked as spam.

1. Log in to cPanel and go to Email > Spam Filters.
2. Ensure SpamAssassin is enabled.
3. Adjust the spam threshold score (default is 5). Lower values are more aggressive:
   • 5 — Standard filtering (recommended)
   • 3 — Aggressive (may catch some legitimate mail)
   • 8 — Lenient (more spam may get through)
4. Optionally enable Auto-Delete to automatically discard messages above a certain score.

Allowlists and Blocklists

• Allowlist (whitelist): Add trusted sender addresses or domains that should never be marked as spam.
• Blocklist (blacklist): Add addresses or domains that should always be treated as spam.

In cPanel, these are found under Spam Filters > Show Additional Configurations.

Configuring Spam Settings in Google Workspace

1. In the Google Admin console, go to Apps > Google Workspace > Gmail > Spam, phishing, and malware.
2. Options include:
   • Approved senders — Bypass spam filters for specific addresses or domains.
   • Blocked senders — Always send messages from these senders to spam.
   • Inbound gateway — If you use a third-party spam filter before Gmail.

Users can also mark messages as spam or “not spam” to train Gmail’s filters.

Configuring Spam Settings in Microsoft 365

1. In the Microsoft 365 Security center, go to Email & collaboration > Policies & rules > Threat policies > Anti-spam.
2. Edit the Anti-spam inbound policy to adjust:
   • Spam and high-confidence spam actions (move to junk, quarantine, delete).
   • Allowed/blocked senders and domains.
   • Bulk email threshold.

Best Practices

• Do not disable spam filtering — Even if you get occasional false positives, the protection is worth it.
• Check your spam/junk folder regularly — Legitimate emails are occasionally misclassified.
• Train your filter — Consistently mark spam as spam and false positives as “not spam.”
• Use email authentication — Configure SPF, DKIM, and DMARC on your domain so your outgoing messages are not flagged as spam by others.
• Avoid publishing your email address publicly — Use contact forms on your website instead to reduce harvesting.
• Unsubscribe carefully — Use the unsubscribe link only for known legitimate senders. For obvious spam, mark as spam instead of clicking links.

When Legitimate Email Is Being Blocked

If a specific sender’s messages consistently go to spam:

1. Ask the sender to verify their SPF, DKIM, and DMARC records.
2. Add the sender to your allowlist.
3. Check if the sender’s IP or domain is on a public blocklist.
4. Mark their messages as “not spam” to train your filter.