Why Is My Email Going to Spam?¶
A troubleshooting guide for emails that land in spam folders instead of the inbox.
Quick Checklist¶
Run through these common causes:
- SPF record configured - Is your sending server authorised?
- DKIM enabled - Are your emails signed?
- DMARC published - Do you have a policy?
- No blacklisting - Is your IP/domain on a blacklist?
- Good content - Does your email look legitimate?
- Proper formatting - HTML well-formed, text version included?
Authentication Issues¶
Missing or Failed SPF¶
SPF tells receiving servers which servers can send email for your domain.
Check your SPF:
Look for: A TXT record starting with v=spf1
Common fixes:
- Add missing include: for your email provider
- Ensure your sending IP is authorised
- Don't exceed 10 DNS lookups
Missing or Failed DKIM¶
DKIM adds a digital signature proving the email is genuine.
Check if DKIM is set up:
1. Send an email to a Gmail address
2. Open it and click "Show original"
3. Look for dkim=pass
If DKIM fails: - Verify DKIM is enabled in your email provider - Check the DNS record is published correctly - Ensure the selector matches
No DMARC Policy¶
DMARC ties SPF and DKIM together and tells servers what to do when checks fail.
Check your DMARC:
If missing, add a basic policy:
Reputation Issues¶
IP Address Blacklisted¶
Your sending IP might be on a spam blacklist.
Check blacklists: - MXToolbox Blacklist Check (mxtoolbox.com/blacklists.aspx) - MultiRBL (multirbl.valli.org)
If blacklisted: 1. Identify the blacklist 2. Follow their removal process 3. Fix the underlying issue (compromised account, spam complaints)
Domain Reputation¶
New domains or domains with poor history may be flagged.
Improve domain reputation: - Start with low volume, increase gradually - Ensure high engagement (opens, replies) - Keep complaint rates below 0.1% - Remove bouncing addresses promptly
Sending IP Reputation¶
Shared IPs can be affected by other senders.
Check IP reputation: - Google Postmaster Tools (for Gmail) - Microsoft SNDS (for Outlook/Hotmail) - Talos Intelligence (talosintelligence.com)
Content Issues¶
Spam Trigger Words¶
Certain words and phrases trigger spam filters:
Avoid or use carefully: - "FREE!!!", "Act now!", "Limited time" - "Click here", "Buy now", "Order today" - Excessive punctuation (!!!, ???) - ALL CAPS TEXT - "Congratulations", "You've won"
Poor HTML Formatting¶
Badly formatted HTML raises red flags.
Best practices: - Use proper HTML structure - Keep HTML simple and clean - Don't use excessive inline styles - Include a plain text version - Keep image-to-text ratio balanced
Suspicious Links¶
Avoid: - URL shorteners (bit.ly, tinyurl) - Mismatched link text and URL - Links to blacklisted domains - Too many links
Best practices: - Use full, visible URLs - Ensure link text matches destination - Link to reputable domains - Include your own domain in links
Missing Unsubscribe Link¶
Marketing emails must have an easy unsubscribe option.
Requirements: - One-click unsubscribe link - Visible and easy to find - Actually works (honour requests within 10 days)
Technical Issues¶
Missing Reverse DNS (PTR)¶
Your sending IP should have a PTR record pointing back to your domain.
Check PTR:
If missing: Contact your hosting provider to set up reverse DNS.
Invalid From Address¶
The "From" address should be valid and match your domain.
Avoid:
- noreply@ addresses (some filters penalise these)
- Generic addresses that don't accept replies
- Addresses that bounce
Inconsistent Headers¶
Email headers should be consistent and properly formatted.
Check for: - Matching envelope and header From addresses - Valid Message-ID - Proper Date header - Consistent sending domain
Testing Your Emails¶
Mail-Tester¶
- Go to mail-tester.com
- Send your email to the provided address
- Get a detailed spam score and recommendations
GlockApps¶
Tests delivery across multiple providers (Gmail, Outlook, Yahoo, etc.)
Manual Testing¶
Send test emails to: - Gmail (check Spam folder and "Show original") - Outlook.com - Yahoo Mail
Improving Deliverability¶
Warm Up New Domains/IPs¶
Don't send high volume immediately:
| Week | Daily Volume |
|---|---|
| 1 | 50-100 |
| 2 | 200-500 |
| 3 | 500-1000 |
| 4+ | Gradually increase |
Maintain List Hygiene¶
- Remove bounced addresses immediately
- Remove unengaged subscribers (no opens in 6+ months)
- Use double opt-in for new subscribers
- Never buy email lists
Monitor Metrics¶
Healthy benchmarks: - Bounce rate: < 2% - Spam complaint rate: < 0.1% - Unsubscribe rate: < 0.5%
Provider-Specific Tips¶
Gmail¶
- Register with Google Postmaster Tools
- Include physical address in marketing emails
- Authenticate with SPF, DKIM, and DMARC
- High engagement improves inbox placement
Microsoft (Outlook, Hotmail)¶
- Register with Microsoft SNDS
- Join their Junk Email Reporting Program
- Consistent sending patterns help
- IP reputation is heavily weighted
Yahoo¶
- Implement DMARC
- Low complaint rates are critical
- Consistent "From" addresses
- Good engagement metrics
Still Going to Spam?¶
If you've checked everything:
- Review recent changes - Did you change sending provider, content, or volume?
- Check individual bounces - Some providers give specific reasons
- Contact the provider - Gmail, Microsoft, etc. have postmaster tools and support
- Consider a dedicated IP - Isolate your reputation from others
- Use an email deliverability service - They can diagnose complex issues