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How to Improve Email Deliverability

Actionable steps to get more emails into inboxes. Prioritized by impact — start with what matters most.

1. Fix email authentication (highest impact)

This is the single most impactful thing you can do. Without SPF, DKIM, and DMARC, ISPs have no way to verify you're a legitimate sender.

  • Add an SPF record that includes your email provider's sending servers
  • Configure DKIM signing for your domain
  • Set up a DMARC policy (start with p=none for monitoring)

RelayPost configures DKIM and SPF automatically during domain verification. See our authentication guide.

2. Clean your email list

Sending to invalid or inactive addresses damages your reputation. Remove:

  • Hard bounces — addresses that don't exist. Remove immediately and permanently.
  • Soft bounces — temporary failures. Remove after 3 consecutive soft bounces.
  • Inactive recipients — users who haven't opened in 6+ months. Move to a re-engagement segment or remove.
  • Role addresses — info@, admin@, support@ — these often trigger spam filters.

3. Warm up new domains and IPs

New domains have zero reputation. ISPs are cautious about unknown senders. Gradually increase volume over 4-8 weeks:

  • Week 1-2: 50-200 emails/day to your most engaged recipients
  • Week 3-4: 500-1,000 emails/day
  • Week 5-8: Double weekly until you reach target volume

During warmup, only send to recipients who are likely to open and engage.

4. Optimize email content

  • Write clear subject lines — avoid ALL CAPS, excessive punctuation, and spam trigger words
  • Include both HTML and plain-text versions
  • Maintain a good text-to-image ratio — don't send image-only emails
  • Use full URLs instead of URL shorteners
  • Include a visible unsubscribe link
  • Keep your From name and address consistent

5. Monitor and react

Set up monitoring for these metrics and react quickly to any degradation:

  • Bounce rate — target below 2%. Investigate any spike immediately.
  • Complaint rate — target below 0.1%. This is the most damaging metric.
  • Inbox placement — use seed testing or RelayPost's deliverability dashboard.
  • Domain reputation — check Google Postmaster Tools weekly.

6. Use a dedicated email delivery service

Self-hosted mail servers require constant maintenance — IP reputation management, bounce processing, feedback loop handling, and authentication configuration. A dedicated service like RelayPost handles all of this automatically.

Key benefits of using a delivery service:

  • Pre-warmed, high-reputation sending infrastructure
  • Automatic bounce and complaint suppression
  • DKIM/SPF configured automatically
  • Real-time delivery monitoring and webhooks

Related guides

Frequently asked questions

What is the fastest way to improve email deliverability?

Fix your email authentication first. Adding correct SPF, DKIM, and DMARC records has the biggest immediate impact. Most deliverability problems start with missing or misconfigured authentication.

How long does it take to see deliverability improvements?

Authentication fixes take effect within hours. Reputation improvements take 2-4 weeks of consistent, clean sending. Full domain warmup for new domains takes 4-8 weeks.

Does switching email providers improve deliverability?

It can. A provider with high-reputation sending infrastructure, automatic authentication, and proper suppression management gives you a better starting point. But you still need clean lists and good content.

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