The Email Deliverability Audit Checklist
If your cold email performance has been declining and you are not sure why, a deliverability audit is the fastest way to find the problem. Most deliverability issues come from a small number of common causes, and working through a structured checklist catches them quickly.
Here are 25 points to check, organized from most critical to least. Work through them in order and you will either find your problem or confirm that your infrastructure is solid.
Authentication (Points 1-4)
1. SPF record is valid and includes all sending services. Check your SPF record with MXToolbox. Confirm that every service you send email through (Google Workspace, your outreach platform, any marketing tools) is included. A missing include means those emails fail SPF authentication.
2. DKIM is configured and passing. Send a test email and check the headers for a valid DKIM signature. Each sending service needs its own DKIM key configured. Missing DKIM on any service means those emails lack the cryptographic signature that proves authenticity.
3. DMARC record exists and is set to at least p=quarantine. Check your DMARC record. If it is set to p=none, you are monitoring but not protecting. Move to p=quarantine for active protection. The DMARC report email address should be an inbox you actually check.
4. SPF record has fewer than 10 DNS lookups. SPF has a hard limit of 10 DNS lookups. Each include: directive counts as one. Exceeding 10 causes SPF to fail entirely, which is worse than not having SPF at all. Use an SPF flattening tool if you are near the limit.
Domain and IP Reputation (Points 5-9)
5. Domain is not on any major blacklists. Check all sending domains against Spamhaus, Barracuda, SORBS, SpamCop, and other major blacklists. Use MXToolbox or a similar multi-list checker. One blacklisting can tank deliverability across all recipients whose servers check that list.
6. Google Postmaster Tools shows healthy domain reputation. If you send to Gmail recipients (and you almost certainly do), set up Google Postmaster Tools for each sending domain. Check domain reputation: High or Medium is acceptable. Low or Bad requires immediate investigation.
7. Sending IP is clean. If you use dedicated IPs, check their reputation separately from your domain. Shared IPs (like those on Google Workspace) are managed by the provider, but dedicated SMTP IPs are your responsibility.
8. Domain age is sufficient. New domains (less than 30 days old) have inherently low trust. If you are sending from a very new domain, ensure you completed a proper warm-up period before scaling volume.
9. Historical sending patterns are consistent. Sudden spikes in sending volume raise red flags. Check your sending history for the past 90 days. Volume should be relatively consistent day-to-day, with gradual increases rather than sudden jumps.
List Quality (Points 10-15)
10. Bounce rate is below 2 percent. Check your bounce rate across all campaigns for the past 30 days. Above 2 percent indicates a list quality problem that needs immediate attention. Above 5 percent is an emergency.
11. Spam complaint rate is below 0.1 percent. Check your complaint rate (available through Google Postmaster Tools and most sending platforms). Above 0.1 percent means too many recipients are marking your emails as spam.
12. All email addresses are verified before sending. Check whether your workflow includes email verification as a step before campaign launch. If not, implement it immediately. This single change has the largest impact on deliverability of any practice.
13. Catch-all domains are handled separately. Check whether catch-all addresses are segmented and sent at reduced volume. If they are mixed in with verified-valid addresses, separate them.
14. Hard bounces are permanently removed. Check that hard-bounced addresses are automatically and permanently excluded from all future sends. They should never be emailed again.
15. List freshness is maintained. Check the average age of records in your sending lists. B2B data decays at 2.1 percent per month. Records older than 90 days should be re-verified before sending.
Sending Practices (Points 16-20)
16. Daily sending volume is within safe limits. Check that each sending account stays within its safe daily limit (100 to 150 for cold outreach from Google Workspace, even though the technical limit is 500).
17. Warm-up is running on all accounts. Check that email warm-up tools are running continuously on all outreach accounts, not just during the initial warm-up period. Stopping warm-up causes reputation to degrade over time.
18. Sending happens during business hours. Check your send time distribution. Emails sent at 3 AM look suspicious to spam filters. Send during the recipient's business hours for both deliverability and engagement benefits.
19. Outreach domains are separate from corporate domain. Confirm that you are not sending cold outreach from your primary corporate domain. If you are, this is the single highest-risk finding in your audit.
20. No more than 2-3 links per email. Check your email templates for link count. More than 3 links in a cold email raises spam filter scores. Ideally, cold emails have zero or one link.
Content and Engagement (Points 21-25)
21. Subject lines avoid spam trigger words. Review your subject lines for words and patterns that trigger spam filters: free, guaranteed, act now, limited time, excessive punctuation, all caps. These add to your spam score even if your infrastructure is clean.
22. Emails are plain text or minimal HTML. Check whether your cold outreach templates use heavy HTML formatting, embedded images, or marketing-style layouts. For cold outreach, plain text or minimal HTML consistently achieves better inbox placement.
23. Unsubscribe mechanism exists. Even for cold B2B outreach, providing an unsubscribe option reduces spam complaints (because recipients have an alternative to the spam button). Check that every outreach email includes an unsubscribe link or clear opt-out language.
24. Open rates are healthy. Check open rates segmented by provider domain. Healthy cold outreach open rates are 30 to 50 percent. If a specific provider (Gmail, Outlook) shows significantly lower open rates than others, you may have a provider-specific deliverability problem.
25. Reply rates are tracking appropriately. Healthy cold email reply rates are 1 to 4 percent on average, with top performers hitting 5 to 10 percent. If reply rates are below 1 percent despite good open rates, the issue might be targeting or messaging rather than deliverability.
Scoring Your Audit
Give yourself 4 points for each item that passes. Total possible: 100 points.
- 90 to 100: Excellent. Your deliverability infrastructure is solid. Focus on content and targeting optimization.
- 75 to 89: Good with room for improvement. Address the failing items in priority order.
- 60 to 74: Significant issues. Pause outreach until the critical items (authentication, blacklist status, bounce rate) are resolved.
- Below 60: Your deliverability infrastructure needs a complete overhaul. Start from Point 1 and work through systematically.
The Connection to Enrichment Quality
Notice how many checklist items (10 through 15) relate directly to data quality. List quality is the foundation of deliverability. The best authentication setup, the cleanest sending infrastructure, and the most compelling email copy will all underperform if you are sending to inaccurate or outdated email addresses.
This is why enrichment quality is not just a data operations concern. It is a deliverability concern. Waterfall enrichment tools like BetterEnrich that verify contacts as part of the enrichment process address multiple audit items simultaneously: verified addresses reduce bounces, accurate contact-company matching reduces complaints, and pay-per-valid pricing ensures you are not paying for data that would fail these checks anyway.
The Bottom Line
Run this audit quarterly, or immediately whenever you notice a decline in outreach performance. Most deliverability problems come from a small number of root causes, and this checklist catches all of them. Fix the failing items in the order listed (authentication first, then reputation, then list quality, then sending practices, then content) and your deliverability will improve methodically.
