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Is your domain ready to send cold email?
Type your domain. We check SPF (including the 10-lookup limit most checkers skip), DKIM, DMARC and MX, and tell you in plain words what to fix. It runs in your browser.
Enter your domain to see SPF, DKIM, DMARC and MX checked in seconds, with the exact record to fix anything that fails.
- 1.Enter the domain you send from, or any email address on it.
- 2.Add your DKIM selector if your provider uses a custom one (Microsoft 365 uses selector1 and selector2).
- 3.Fix anything marked Fix, then anything marked Improve, and check again.
Why these four records decide where your email lands
Mailbox providers check who you are before they read a word you wrote. SPF lists the servers allowed to send as your domain, DKIM signs each message so it cannot be altered on the way, and DMARC tells receivers what to do when either fails. MX shows you can receive mail, which matters because a domain that cannot receive looks like a throwaway.
Since 2024 Gmail and Yahoo require SPF, DKIM and DMARC from anyone sending in volume. Missing one no longer means "slightly worse placement"; it means rejection.
The SPF 10-lookup limit, explained
SPF may trigger at most 10 DNS lookups while it is evaluated: every include, a, mx, ptr, exists and redirect counts, and so does every lookup inside the records you include. Add one more tool that sends email for you (a CRM, a help desk, a newsletter platform) and you can cross the limit without changing a character yourself.
Past 10, SPF returns a permanent error and fails for every receiver, which looks exactly like a deliverability collapse with no obvious cause. The fix is to remove includes for services you no longer use, or replace one with the IP ranges it covers.
Do this automatically
Leads Ranger runs this audit on every connected mailbox, then warms it up and watches the bounces for you.
Straight answers
Questions, answered.
One SPF record that includes only the services that really send for you and ends in ~all, DKIM signing switched on in your email provider with its key published, and a DMARC record that starts at p=none with reporting, then moves to p=quarantine once everything passes. Send cold email from a separate domain so a problem never touches your main one.
Count the includes in your SPF record, remove the ones for services you no longer send through, and avoid the mx and a mechanisms if your provider’s include already covers those servers. If you are still over 10, replace one include with the ip4 and ip6 ranges it resolves to, and re-check whenever that provider changes them.
DKIM keys live under a selector chosen by your provider, and there is no way to list them. The checker tries the most common selectors. If your provider uses another one, find it in your email settings (or in the DKIM-Signature header of an email you sent, after s=) and enter it.
No. The lookups run in your browser against public DNS resolvers (Google’s, with Cloudflare’s as a fallback). Nothing about the domain you check is sent to us or stored.
Go deeper
Guides from the Ranger Playbook
Guide · 10 min read
SPF Too Many DNS Lookups: What Dynamic SPF Is and When You Need It
Why SPF breaks silently at ten DNS lookups, how to count yours, the four ways to fix it including flattening and dynamic SPF, and why DMARC without SPF is not the disaster it sounds like.
Read the guide→Guide · 9 min readSPF, DKIM and DMARC: The 20-Minute Setup That Decides Your Cold Email
A plain-English guide to the three DNS records every sender needs, what each one actually proves, how to set them up correctly, and the mistakes that quietly break them.
Read the guide→Guide · 9 min readDo I Need DMARC for Cold Email? Yes, and Here Is Exactly Why
What DMARC does, why Google and Yahoo made it effectively mandatory, which policy to start on, and the two mistakes that break legitimate mail the day you publish a record.
Read the guide→Guide · 8 min readGoogle and Yahoo Sender Requirements: The Plain-English Checklist
What Google and Yahoo actually require from senders, which rules apply to small senders too, the 0.3% number that decides your fate, and how to check whether you comply today.
Read the guide→Free during the open pilot
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