Free tool · no signup
Sending-domain checker
Mailbox providers check three DNS records before they trust your email. SPF, DKIM and DMARC. Miss any one of them and your cold email lands in spam. Check your domain in one click.
Enter a domain and we read its public SPF, DKIM and DMARC records.
Sending cold email to UK companies? Leadistry finds the leads and sends from your own inbox. Warm-up and this exact health check are built into every pipeline. Try 25 free leads, no card needed.
What mailbox providers look for
Which servers may send as this domain? One DNS TXT record lists your providers.
A signature that proves the mail came from you, and that nobody changed it.
The policy that tells providers what to do when SPF and DKIM both fail.
The three records, in plain English
SPF answers one question. Which servers may send as this domain? It is a single TXT record. It lists your provider: Microsoft 365, Google Workspace, your marketing tool. Mail from anywhere else fails the check. DKIM answers a second question. Did this message really come from the domain, unchanged? Every message carries a signature. Providers check it against a public key in your DNS. DMARC ties the two together. It tells the provider what to do with mail that fails both. It also says where to send reports, so you can see who is spoofing you.
Since early 2024, Gmail and Yahoo have required bulk senders to pass all three. Microsoft applies much the same pressure. A domain with no DMARC record is not just untidy. It is measurably more likely to land in spam. It is also easy for anyone to spoof.
Common failure patterns
Four failures come up again and again. Two SPF records on one domain, which is itself an error, so providers ignore both. An SPF record that breaks the 10-lookup limit because include: entries are stacked up. DKIM switched on at the mail provider, but the CNAME records never added at the registrar. And a p=none DMARC record left alone for years, which meets the letter of the rule but tells providers you never moved to an enforced policy. Each one is a ten-minute fix once you can see it. That is what this checker is for.
Frequently asked questions
Also free: the email verifier. Deliverability guide: SPF, DKIM and DMARC for UK cold email.
What is SPF?
It stands for Sender Policy Framework. It is a DNS TXT record. It lists the servers allowed to send email for your domain. If your mail arrives from a server that is not on the list, providers get suspicious. You get one record per domain. Two SPF records is itself an error.
What is DKIM?
It stands for DomainKeys Identified Mail. Your mail server signs every message you send with a private key. The matching public key sits in your DNS. The receiving provider checks the signature. That proves the message came from your domain, and that nobody changed it on the way. Without DKIM, Gmail and Microsoft treat bulk senders with real suspicion.
What is DMARC?
It is the policy layer that sits on top of SPF and DKIM. It tells providers what to do when a message fails both checks. Do nothing (p=none). Send it to spam (p=quarantine). Or reject it outright (p=reject). Since 2024, Google and Yahoo have required bulk senders to publish at least a p=none record. So having none at all hurts your inbox placement.
All three records pass but my email still goes to spam. Why?
Authentication is the entry ticket, not the whole game. Your content, your volume, your bounce rate and your history all feed the spam decision. Two causes come up again and again. Sending too much, too fast, from a fresh domain with no warm-up. And a high bounce rate from a list nobody checked.
Do I need a separate domain for cold outreach?
Many senders use a close variant of their main domain for outreach. That keeps any reputation damage off the main one. It works. But the variant needs its own SPF, DKIM and DMARC records. It also needs several weeks of warm-up before you send real volume.
Records in order? Now fill the pipeline.
25 free leads, each with a verified website and email. Send from your own mailbox, with warm-up built in. No card.
Start free with 25 leads →✓ No card · ✓ 25 free leads · ✓ Cancel anytime