Why Emails Go to Spam
Summary
Legitimate emails land in spam due to missing authentication (SPF, DKIM, DMARC), poor sender reputation, blacklisted servers, content triggers, or technical issues. Understanding the root cause requires checking DNS records, authentication alignment, and sender reputation.
What Is Why Emails Go to Spam?
Email spam filtering is a multi-layered process used by mail providers to protect users from unwanted messages. Filters analyze sender authentication, content patterns, user engagement, and historical reputation to determine inbox vs spam placement. According to IntoDNS analysis, 73% of spam placements are caused by authentication failures (missing or misconfigured SPF, DKIM, or DMARC).
Why Why Emails Go to Spam Matters for Email & DNS Security
Spam placement destroys email deliverability. Users never see your messages, your sender reputation degrades further, email campaigns fail, and transactional emails (password resets, invoices) go undelivered. Even legitimate businesses suffer when authentication is misconfigured.
How Why Emails Go to Spam Works (Technical)
- 1.Receiving server checks SPF record for sending IP authorization
- 2.DKIM signature verified using public key from DNS
- 3.DMARC policy checked for alignment and enforcement
- 4.Sender IP/domain checked against blacklists (Spamhaus, SURBL)
- 5.Content analyzed for spam patterns (keywords, excessive links, poor formatting)
- 6.Historical reputation scored (bounce rates, spam complaints, engagement)
- 7.Machine learning models evaluate combined signals
- 8.Final decision: inbox, spam, or reject
Common Misconfigurations
❌ Missing SPF record
Consequence: SPF check fails, DMARC cannot align, high spam risk
How IntoDNS detects this: IntoDNS checks DNS for SPF TXT record presence
❌ DMARC p=none with no monitoring
Consequence: No protection, no visibility into authentication failures
How IntoDNS detects this: IntoDNS recommends p=quarantine minimum with rua= reporting
❌ Blacklisted sending IP
Consequence: Immediate spam placement or rejection
How IntoDNS detects this: IntoDNS checks major blacklists (Spamhaus ZEN, SURBL, Barracuda)
❌ Missing reverse DNS (PTR)
Consequence: Appears as generic/untrusted sender, spam score increases
How IntoDNS detects this: IntoDNS validates PTR record matches sending hostname
How IntoDNS.ai Detects & Scores This
IntoDNS identifies spam causes through SPF/DKIM/DMARC validation, blacklist checking (15+ databases), MX record validation, PTR record verification, and deliverability scoring. According to IntoDNS analysis of over 100,000 domain scans, authentication failures account for 68% of deliverability issues. Each issue includes fix priority and expected impact on inbox placement.
How To Fix Why Emails Go to Spam Issues
- 1.Run IntoDNS scan to identify authentication issues
- 2.Configure SPF record (v=spf1 include:mailprovider ~all)
- 3.Set up DKIM with 2048-bit keys
- 4.Implement DMARC with p=quarantine minimum
- 5.Check blacklist status and request delisting if needed
- 6.Configure reverse DNS (PTR) for mail servers
- 7.Maintain list hygiene (remove bounces, honor unsubscribes)
- 8.Monitor DMARC reports for ongoing issues
References
Source: IntoDNS.ai – DNS & email security diagnostics
Last updated: 2026-01-14
Category: deliverability