Email Deliverability Best Practices for Small Businesses

May 2026 · 11 min read

Email deliverability — the ability to consistently land in your recipients' inboxes rather than their spam folders — is critical for any business that relies on email communication. Here are proven practices to maximise your deliverability.

1. Authenticate Your Domain Properly

This is the single most important step. Configure all three authentication protocols:

• SPF — Authorise your sending servers
• DKIM — Sign your emails cryptographically
• DMARC — Set a policy for failed authentication (use p=reject)

Without proper authentication, ISPs have no reason to trust your emails, and many will filter them to spam by default.

2. Warm Up Your Domain

New domains have no sending reputation. Start with low volumes and gradually increase over 2-4 weeks. ISPs track domain age and sending patterns — a new domain sending thousands of emails immediately looks suspicious.

• Week 1: 10-50 emails/day
• Week 2: 50-200 emails/day
• Week 3: 200-500 emails/day
• Week 4+: Gradually increase to full volume

3. Monitor Your Bounce Rate

Keep your bounce rate below 5%. High bounce rates signal to ISPs that you're sending to invalid addresses — a strong spam indicator.

• Hard bounces (invalid addresses) should be immediately removed from your sending lists
• Soft bounces (temporary failures) should be retried but tracked — persistent soft bounces indicate a problem

4. Keep Complaint Rates Low

Complaint rates should stay below 0.1% (one complaint per 1,000 emails). When recipients mark your emails as spam, it directly damages your sender reputation.

For transactional email, complaints should be near zero since recipients expect these messages. If you're getting complaints on transactional emails, review your sending patterns — you may be sending too frequently or including unwanted content.

5. Separate Transactional and Marketing Email

Never mix transactional and marketing email on the same sending infrastructure. Marketing emails inherently have higher complaint and unsubscribe rates, which can drag down deliverability for your critical transactional messages.

Use different subdomains or different providers for each stream:

• mail.yourdomain.com for transactional
• marketing.yourdomain.com for promotional

6. Use a Consistent "From" Address

Stick to consistent, recognisable sender addresses. Don't change your "From" name or address frequently — it confuses both recipients and spam filters.

7. Set Up Reverse DNS

Ensure your mail server's IP address has a PTR record that matches your sending hostname. Many ISPs reject or filter email from servers without valid reverse DNS.

8. Monitor Blacklists

Regularly check if your sending IP or domain appears on email blacklists. Tools like MXToolbox provide free blacklist monitoring. If you're listed, follow the blacklist's removal process immediately.

9. Write Clear Subject Lines

Avoid spam trigger patterns in subject lines:

• No ALL CAPS
• No excessive punctuation (!!!, ???)
• No misleading or deceptive subjects
• Keep subjects concise and relevant

10. Monitor and Iterate

Deliverability isn't set-and-forget. Monitor your DMARC reports, track bounce rates, and watch for any sudden drops in open rates (which can indicate deliverability issues). Set up alerts for when metrics exceed your thresholds.