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.