In short
An email deliverability checker reads the DNS records that decide whether your cold email reaches an inbox: SPF, DKIM, DMARC and MX. Enter a domain and this tool reports what is published, what is missing, and what each result means for outbound. It checks public records only and stores nothing.
Public DNS records only. Runs in your browser; nothing is sent to us or stored.
What each record does
Four records decide whether a receiving server trusts mail claiming to come from your domain. Three of them are yours to publish, and most businesses running outbound for the first time are missing at least one.
- SPF lists the servers allowed to send as your domain. A record pointing at a provider you left years ago is worse than none, because it fails rather than staying silent.
- DKIM signs every message so the receiver can prove nothing was altered on the way. It lives at a selector, which is why a checker can only test the common ones.
- DMARC tells receivers what to do when SPF or DKIM fails, and where to send the reports that show you who is sending as you. Starting at
p=noneis normal. - MX shows where your mail is received. It will not fix deliverability on its own, but a mismatch between where you receive and what SPF allows is a common cause of failure.
Why we built this
We run outbound for insurance agencies, mortgage brokers and other firms that sell to consumers, and the same thing happens at the start of nearly every engagement: the first campaign would have failed in the mail server rather than in the market. An SPF record aimed at a host that stopped sending years ago. No DKIM. No DMARC at all.
Fixing that is unglamorous and it is the highest-return hour in the whole setup, so we made the diagnostic part free. If the results here look bad, they are fixable, and you do not need us to fix them.
Frequently asked questions
What do SPF, DKIM and DMARC actually do?
SPF lists which servers may send mail using your domain. DKIM signs each message so the receiver can prove it was not altered. DMARC tells receivers what to do when a message fails those checks, and where to send reports. Providers treat all three as evidence that you are who you claim to be.
Why does this matter before a cold campaign?
A domain that fails authentication lands in spam no matter how good the copy is. Most brokerages and agencies we audit have an SPF record pointing at a host that stopped sending years ago, no DKIM, and no DMARC policy at all. Fixing that is the first thing we do in an engagement, before a single message goes out.
Why does the DKIM result say "not found" when we have DKIM?
DKIM records live at a selector you choose, and a selector can be any string. This tool tries the selectors the major providers use, so a "not found" means DKIM was not at any of those. It does not prove DKIM is missing. If you know your selector, check it directly with your provider.
Do you store the domains people check?
No. The lookups run in your browser against public DNS resolvers. Nothing is sent to us and nothing is recorded.
My records are broken. What now?
SPF and DMARC are DNS edits you or your IT provider can make in an afternoon. DKIM is enabled in your mail provider, which then gives you the record to publish. If you would rather it were handled alongside the outbound itself, that is part of what we set up.
If authentication is the least of what is broken, the wider problem is usually the pipeline itself. See how we build and run outbound, or the playbook on buying leads versus building your own pipeline.
