Email Deliverability Audit: A 15-Point Checklist

Run this audit once a quarter, or any time delivery changes.

Authentication (4)

1. SPF passes and has fewer than 10 lookups.
2. DKIM signs every message with a 2048-bit key where possible.
3. DMARC exists with a policy and a reporting address.
4. The From domain aligns with SPF or DKIM.

List quality (4)

1. Bounce rate under 2% on the last campaign.
2. Invalid and disposable addresses removed.
3. Inactive subscribers handled by a re-engagement and sunset rule.
4. New sign-ups verified in real time.

Content and sending (4)

1. Unsubscribe link visible and one-click header present.
2. Plain-text version included and images have alt text.
3. No URL shorteners, mismatched links or oversized images.
4. Volume is steady and sent from consistent domains and IPs.

Monitoring (3)

1. Spam complaint rate tracked and under 0.1%.
2. Seed or test inboxes checked for placement.
3. Postmaster tools (Google, Microsoft) reviewed.

How to use the score

Fix the first failed item in each group before moving on. List quality is usually the quickest win; start with the bulk verifier.

How to score yourself

Give one point for each item that is clearly true and a half point if it is partly true. Be honest: the score is for you.

• 13 to 15: strong. Keep monitoring and re-run the audit every quarter.
• 9 to 12: solid with gaps. Fix the lowest-scoring group first.
• 5 to 8: at risk. Expect inconsistent inbox placement and fix authentication and list quality before sending more volume.
• Below 5: stop large sends until the basics are in place.

The fixes that usually move the score most

1. Publish SPF, DKIM and DMARC and confirm alignment on a real message.
2. Verify the list and remove addresses that bounce.
3. Add a one-click unsubscribe and honour it the same day.
4. Set up a basic dashboard: bounce rate, complaint rate, unsubscribes and delivered volume per campaign.

How to find the evidence

For each item, note where the proof lives: the DNS record, the message headers, a verification report, a dashboard screenshot. An audit with no evidence is an opinion. Save the evidence with the date so the next audit has something to compare.

Cover the list part first

List quality is the item people postpone and the one with the quickest result. Run the whole list through the bulk verifier and note the share of invalid addresses as your baseline.