How to keep your cold email out of the spam folder
In short: Staying out of spam comes down to five things: authenticate (SPF, DKIM, DMARC), warm up new domains, send to clean lists, write human copy, and test before you scale. No single trick fixes placement; these work together. Free tools cover each step, starting with the Spam Word Checker for your copy.
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1. Authenticate your domain
This is the foundation. Without SPF, DKIM and DMARC, your mail looks unverified and filters distrust it by default. Check all three: SPF (valid and under 10 lookups), DKIM (key published), and DMARC (at least a published policy). Fix any gaps before sending a single cold email.
2. Warm up new domains
A brand-new domain sending hundreds of cold emails on day one looks exactly like spam. Ramp volume gradually over several weeks so mailbox providers build trust in your sending. Plan the ramp with the Warm-Up Calculator rather than guessing.
3. Send to clean lists
Bad lists cause bounces, spam traps and complaints, the fastest routes to a blacklist. Verify addresses before sending, remove role accounts and obvious traps, and never buy lists. Clean lists protect the sender reputation everything else depends on.
4. Write human copy
Cold email should read like one person wrote to another. Avoid stacked trigger words, ALL CAPS, heavy images and multiple links. A short, plain message with one clear ask performs best. Run your draft through the Spam Word Checker and preview it on mobile with the Mobile Email Preview.
5. Test before you scale
Before a big send, pull a test message's header with the Email Header Analyzer to confirm SPF, DKIM and DMARC all pass, and check your IP and domain on the Blacklist Checker. Scaling a campaign that already fails these checks just multiplies the damage.
Check your copy before you send
Score your subject and body for the patterns that trip spam filters, then fix them fast.
Open the Spam Word Checker →All free tools