Cold email only works if it reaches the inbox. When it doesn't, the usual suspects are the same: authentication gaps, list quality, copy that trips filters, and infrastructure that was never warmed.
This is the checklist we use when a domain starts slipping into spam.
1. Authentication is incomplete or wrong
Receivers check SPF, DKIM, and DMARC before they trust a message. Missing or broken records are one of the fastest ways to land in spam.
- SPF says which servers may send for your domain
- DKIM cryptographically signs the message
- DMARC tells receivers what to do when SPF/DKIM fail
Check your live records with a free SPF checker, DKIM checker, and DMARC checker. Or run all three at once with the email authentication checker.
If SPF is over the 10-lookup limit, fix that first — it causes permanent errors at many providers.
2. The list was never verified
High bounce rates destroy reputation fast. Role accounts (info@, admin@), typos (gnail.com), and disposable addresses all hurt.
Before every campaign, run the list through a free email verifier. Remove anything flagged as invalid, disposable, or high-risk. Deduplicate with the email list deduper so you are not hammering the same inbox twice.
Aim for under 1% hard bounces. Above 3–5% and you are training filters to treat you as bulk junk.
3. The domain is cold or blacklisted
New domains with no sending history look risky. So do domains that appear on public blocklists.
Use the domain health and blacklist checker to inspect MX, SPF, DMARC, and major DNSBLs (Barracuda, SpamCop, SORBS, PSBL). If you are listed, pause outbound, clean the list, and remediate before scaling again.
For secondary domains used only for outbound, the secondary domain finder helps you pick lookalikes that are still available.
4. Copy trips content filters
Spam filters still weight trigger phrases, excessive punctuation, ALL CAPS, and link shorteners.
Paste your draft into the cold email spam word checker and the subject line checker. Fix highlights before you send. Keep the body short — the email word counter is a useful constraint (most strong first-touch emails sit under ~125 words).
5. Volume ramped too fast
Jumping from zero to thousands of emails per day on a fresh inbox is a classic spam signal. Warm gradually.
The email warmup calculator turns a daily volume target into inbox count, domain count, and a week-by-week ramp. Use it before you buy infrastructure, not after reputation is already burned.
A simple order of operations
- Authenticate the domain (SPF, DKIM, DMARC)
- Verify and clean the list
- Check domain health / blocklists
- Score subject and body for spam risk
- Warm the fleet, then scale
Most “cold email is dead” complaints are really “deliverability was never set up.” Fix the stack first; the copy only matters if it arrives.
If you want the full infrastructure built — domains, inboxes, warmup, and sending — start a build and we will map it to your volume.