Cold Email Deliverability Audit: 15-Point Checklist
Your cold emails are not getting replies. Before you rewrite your copy, change your subject lines, or blame your prospect list, run a deliverability audit. The problem might not be what you are saying. It might be that your emails are not reaching the inbox in the first place.
This 15-point checklist systematically diagnoses deliverability issues in your cold email setup. Work through each item in order. Most deliverability problems are found within the first five checks.
1. SPF Record Check
Look up your sending domain's SPF record using MXToolbox or Google Admin Toolbox. The SPF record should include every service that sends email on behalf of your domain: your email hosting provider (Google Workspace, Microsoft 365), your cold email platform, and any other sending services.
Common problems: missing include statements for your cold email platform, exceeding the 10 DNS lookup limit (which causes the entire SPF record to fail), or having multiple SPF records on the same domain (only one is allowed).
Fix: consolidate all authorized senders into a single SPF record. If you are near the 10-lookup limit, consider using SPF flattening services that replace nested lookups with direct IP references.
2. DKIM Signing Check
Send a test email from your cold email domain and inspect the email headers. In Gmail, click the three dots menu and select "Show original." Look for the DKIM-Signature header and verify that dkim=pass appears in the authentication results.
Common problems: DKIM not configured for the cold email platform (only configured for the email hosting provider), incorrect DNS CNAME records for DKIM selectors, or key mismatch between the signing key and the published DNS record.
Fix: follow your cold email platform's DKIM setup guide exactly. Each platform uses specific selectors and key formats. After setup, send another test email to confirm dkim=pass.
3. DMARC Record Check
Look up your DMARC record (a TXT record at _dmarc.yourdomain.com). At minimum, you should have a record with p=none to start monitoring. Verify that both SPF and DKIM align with your DMARC configuration.
Common problems: no DMARC record at all (increasingly penalized by Gmail and Microsoft), misalignment between the From domain and the SPF/DKIM domains, or aggregate report email not monitored.
Fix: add a DMARC record if missing. Start with p=none and monitor aggregate reports for 2-4 weeks. Review reports for alignment failures and fix them before advancing to stricter policies.
4. Domain Age Check
How old is your sending domain? Domains less than 30 days old face heavy scrutiny from mailbox providers. Domains less than 90 days old are still in the trust-building phase.
If your domain is less than 30 days old, you should still be in warmup, not sending real campaigns. If it is 30-90 days old, send at reduced volumes with extra attention to engagement metrics.
5. Bounce Rate Check
Review your bounce rate across your last 5-10 campaigns. Calculate it per campaign and overall. If any campaign exceeds 2% bounce rate, that campaign damaged your reputation.
If your overall bounce rate is above 1%, your list verification needs improvement. Run your list through comprehensive verification including catch-all resolution. The goal is a bounce rate under 0.5% for cold email.
6. Spam Complaint Rate Check
Check Google Postmaster Tools for your spam complaint rate. If it exceeds 0.3%, you have a complaint problem. If you send more than 5,000 emails per day to Gmail, your threshold is 0.1%.
High complaint rates usually indicate one of three problems: you are emailing people who did not expect to hear from you (targeting issue), your content is irrelevant or aggressive (messaging issue), or your unsubscribe mechanism is not working or not visible (compliance issue).
7. Domain Reputation Check
Check Google Postmaster Tools for your domain reputation rating. High is optimal. Medium is acceptable. Low or Bad requires immediate remediation.
If your reputation is Low or Bad, reduce sending volume immediately and focus on sending only to your most engaged contacts. Follow the reputation recovery process: clean your list, fix any authentication issues, and slowly rebuild trust over 2-8 weeks.
8. Warmup Status Check
Is your warmup tool still running alongside your real campaigns? It should be. Warmup should continue even after you start sending real emails. The warmup engagement signals provide a baseline of positive activity that supports your reputation.
If you stopped warmup when you started real sending, restart it. Most platforms recommend maintaining warmup at 20-30% of your total sending volume indefinitely.
9. Sending Volume Check
Are you exceeding recommended per-inbox limits? The industry standard maximum is 50 emails per day per inbox, with 30-40 being a safer target for cold email.
If you need more volume, add more inboxes and domains rather than increasing per-inbox volume. Check that your volume has been consistent over the past 30 days. Sudden volume spikes trigger provider suspicion.
10. List Quality Assessment
What percentage of your list falls into each verification category? Run a verification report and check the breakdown: valid, invalid, catch-all, unknown, risky, disposable.
If more than 20% of your list is catch-all and those addresses have not been resolved through specialized verification, you are sending to a significant unverified segment. If more than 5% is unknown or risky, those addresses should be removed or verified separately.
11. Content Analysis
Review your email content for spam trigger patterns. Are you using HTML or plain text? (Plain text is better for cold email.) Do you have tracking pixels enabled? (Disable them.) How many links are in your email? (One maximum for first-touch.) Are you using promotional language that triggers spam filters?
Send your email through mail-tester.com to get a spam score. Aim for a score of 9/10 or higher. Anything below 7/10 needs content optimization.
12. Link Analysis
Check every link in your email. Are links tracked through a redirect? (Consider disabling tracking for cold email.) Is your landing page/website on any blocklists? Do links point to reputable, established domains?
If you use a link shortener (bit.ly, etc.), stop. Link shorteners are heavily associated with spam and many spam filters flag them automatically.
13. Sending Speed Check
How fast are your emails going out? If you are sending more than 50-100 emails per hour to a single provider (Gmail, Outlook), you may be hitting rate limits that cause soft bounces or delayed delivery.
Check your platform's sending speed settings. Enable drip sending if available. Space emails throughout the business day rather than sending in large batches.
14. Domain Rotation Check
If you use multiple sending domains, check that volume is distributed evenly. Are all domains in good health? Is any single domain carrying a disproportionate share of your sends?
Check each domain's reputation individually. A single domain with Low reputation in your rotation can drag down the performance of your entire operation if it sends to the same recipient pool.
15. Inbox Placement Test
Run a seed-based inbox placement test using GlockApps, MailReach, or similar. This is the most direct measure of whether your emails are actually reaching the inbox.
Check placement by provider: what is your inbox rate at Gmail vs Outlook vs Yahoo? Provider-specific problems require provider-specific solutions.
If your overall inbox placement is below 80%, there are significant issues to address. Work through the checklist items above to identify and fix the root causes.
Prioritizing Fixes
If your audit reveals multiple issues, prioritize fixes in this order: authentication first (SPF, DKIM, DMARC), then list quality (verification and catch-all resolution), then content optimization, then infrastructure tuning. Authentication and list quality account for the vast majority of cold email deliverability problems. Fix those first and the remaining issues often become easier to diagnose and resolve.
Run this audit monthly for active cold email operations. Deliverability is not a set-it-and-forget-it configuration. It requires ongoing monitoring and maintenance to sustain strong inbox placement over time.
