What is email deliverability?
Email deliverability refers to the ability of your emails to successfully land in recipients' inboxes rather than being filtered to spam folders, quarantined, or rejected entirely. High deliverability is critical for business communication, marketing campaigns, and transactional emails. It depends on technical configuration, sender reputation, and content quality.
Factors affecting deliverability
Technical factors
| Factor | Impact | Priority |
|---|---|---|
| SPF Record | Verifies authorized senders | Critical |
| DKIM Signing | Authenticates message integrity | Critical |
| DMARC Policy | Prevents domain spoofing | High |
| Valid MX Records | Enables proper routing | Critical |
| Reverse DNS | IP credibility | High |
Reputation factors
- Sender IP reputation
- Domain age and history
- Bounce rates
- Spam complaint rates
- Engagement metrics
Content factors
- Spam trigger words
- HTML/text ratio
- Image usage
- Link quality
- Subject line
Deliverability metrics
Key indicators
- Delivery rate: Emails accepted by servers
- Inbox placement: Emails reaching inbox (not spam)
- Open rate: Recipients opening emails
- Click rate: Recipients clicking links
- Bounce rate: Undeliverable emails
- Complaint rate: Spam reports
Healthy benchmarks
| Metric | Good | Warning |
|---|---|---|
| Delivery rate | >97% | <95% |
| Bounce rate | <2% | >5% |
| Complaint rate | <0.1% | >0.3% |
Improving deliverability
Technical setup
1. Configure SPF correctly
v=spf1 include:mailprovider.com -all2. Enable DKIM signing
3. Implement DMARC
v=DMARC1; p=quarantine; rua=mailto:[email protected]Reputation building
- Start with small volumes
- Gradually increase sending
- Remove inactive subscribers
- Process bounces immediately
- Make unsubscribe easy
Content best practices
- Avoid spam trigger words
- Balance images and text
- Use clean, valid HTML
- Include plain text version
- Test before sending
Common deliverability issues
Emails going to spam
Causes:- Missing SPF/DKIM
- Poor sender reputation
- Spam-like content
- Too many links
- Add authentication records
- Warm up IP gradually
- Review content quality
- Reduce promotional language
Emails being rejected
Causes:- Blacklisted IP
- Invalid recipient
- SPF failure
- Rate limiting
- Check blacklist status
- Verify email lists
- Fix DNS records
- Throttle sending
Monitoring deliverability
Tools to use
- Google Postmaster Tools
- Microsoft SNDS
- Sender Score
- MXToolbox
- Mail-tester.com
What to monitor
- Blacklist status
- Authentication results
- Spam scores
- Engagement trends
- Bounce patterns
Email warm-up
When starting with new IP/domain:
1. Send to engaged recipients first
2. Start with small volumes (50-100/day)
3. Increase gradually over weeks
4. Monitor reputation closely
5. Address issues immediately
Email deliverability requires ongoing attention to technical configuration, sender reputation, and content quality to ensure your messages reach their intended recipients.