The Spam Problem

An estimated 85% of all email traffic on the Internet is spam.
This issue results in millions of dollars lost annually due to reduced productivity and increased infrastructure costs. Spammers continue to evolve, finding new ways to bypass common defenses and infiltrate inboxes.

Solving the Problem

Our Spam DNA Filtering® system continuously evolves to stay ahead of spammers. It:

• Gathers real-time spam intelligence from multiple sources.
• Tracks tens of thousands of live spam characteristics ("DNA").
• Uses third-party databases, DNS checks, and formatting tests.
• Runs thousands of evolving tests on every email.

Effectiveness: Blocks 98%+ of spam with virtually zero false-positives.

Weighted Tests

Key principles:

• No single test identifies all spam.
• Some tests may falsely flag legitimate messages.

Our system uses a point-based weighting system:

1. Each test assigns points when failed.
2. If the cumulative score exceeds a threshold, the email is flagged as spam.
3. Customers can customize their spam sensitivity level.

Spam “DNA”

Spam samples are collected through spam traps and user submissions.
These are normalized (removing obfuscation), broken into components, and coded into a DNA fingerprint, much like antivirus signatures. Matching DNA adds spam points to the email.

Zombies, Open Relays, and Spam Sources

• Zombies: Infected computers unknowingly sending bulk spam.
• Open Relays: Unsecured mail servers hijacked by spammers.

To block these:

• We use 15+ blocklist databases, updated hourly.
• Emails from known spam IPs automatically receive spam points.

DNS and RFC Violations

Spammers often ignore Internet standards. We test for issues such as:

• False "HELO/EHLO" identification.
• Missing or invalid reverse DNS records.
• Invalid or missing “A” and “MX” DNS records.
• SPF violations (unauthorized sending domains).
• Improper or missing headers.

Over 1,000 tests are used, always in conjunction with the weighting system.

Elusive Spammers

Spammers use tactics like:

• Binary encoding.
• Hidden HTML.
• Punctuation tricks.
• Misspellings and alternate characters.

Our pre-processors normalize emails by removing obfuscation, decoding hidden formats, and scanning the true content. Spam points are added when deceptive tactics are detected.

Combining the Tests

Each email is assigned a final weighted score:

• Below threshold: Delivered normally.
• Above threshold: Flagged as spam.

What to Do With Spam

User preferences determine the outcome:

• Delete – Removes spam entirely.
• Deliver to Spam Folder – Reviewable in webmail or IMAP, with auto-purge options.
• Tag the Subject – Adds “[SPAM]” for custom filtering in email clients.
• Forward to Alternate Address – Centralized spam review for administrators.

False-Positive Prevention

To protect legitimate emails:

• Reverse filters identify valid email traits.
• ReturnPath provides additional safeguards.
• Bonded Sender Program: Reputable bulk senders bypass filters.
• Sender Score: Rates senders’ reputations (like a credit score).

Safe Lists

Users and domain administrators can define trusted senders that bypass filters.
This is especially useful for newsletters or improperly configured servers.

Exclusive Filtering

For maximum protection, Exclusive Mode blocks all senders not on the Safe List.
Unknown senders are automatically flagged as spam.

Individual User Flexibility

• Domain admins set default spam settings.
• Users can adjust sensitivity or maintain personal Safe Lists.
• Domain-level and user-level Safe Lists work together to ensure delivery of trusted mail.

Network-Level Spam Security

Our system is safeguarded with:

• 24/7 firewall monitoring by Tier 1 Engineers.
• Global filtering rules against abusive sources.
• DoS (Denial of Service) protections.

Directory Harvest Attack Protection

Spammers attempt to discover valid addresses by probing SMTP servers.
We defend by:

• Disconnecting spammers after repeated invalid recipient attempts.
• Throttling subsequent connections.

This prevents address harvesting and protects customer email identities.

Abuse and Blocklist Prevention

We enforce strict policies to protect service integrity:

• Bulk mailing attempts are cut off automatically.
• IP addresses are checked hourly against anti-spam blocklists.
• Blocked IPs are immediately removed from service.
• Fallback routing ensures continued delivery with clean IPs.
• Engineers work directly with blocklist organizations for delisting.

📞 For further assistance, please contact Technical Support at (800) 736-0688 or email techsupport@mi4p.com.