MX
Mail exchangers tell the world where to deliver mail for your domain. Missing or odd MX is a red flag for both inbound and outbound trust.
Confirm MX points at your real provider (Google, Microsoft, etc.) before you warm cold domains.
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Domain Email Health Checker
Type any domain. We do a live DNS lookup against your real authentication records and tell you exactly what's missing, mis-configured, or working. No signup, no logs, no email required.
Step 01
Domain
Just the apex domain — no @ or protocol. Lookup runs server-side.
Or try a known-good domain
What we check
- SPF — sender authorization
- DKIM — message signature (probes common selectors)
- DMARC — policy when SPF or DKIM fail
- MX — can the domain receive mail at all
Step 02
Health report
Run a check to see the report.
Enter a domain on the left.
Or click a sample to see the format.
Deliverability foundation
Great copy cannot save a domain that fails authentication
Inbox placement is a stack: DNS identity, reputation, list quality, and content. This tool does a live, read-only DNS check so you can see what receivers see — before you burn a week of warmup. Pair it with the Spam Word Checker for the content layer.
Records explained
What SPF, DKIM, DMARC, and MX actually do
SPF
Sender Policy Framework lists which servers may send as your domain. Broken SPF is one of the fastest ways cold volume lands in spam.
Keep one SPF record. Too many includes and you hit the 10-lookup limit.
DKIM
DomainKeys Identified Mail cryptographically signs messages. Providers use selectors — if we cannot find a common selector, check your ESP docs.
Rotate keys carefully. A missing selector is not always a failure if your ESP uses a custom name.
DMARC
DMARC tells receivers what to do when SPF/DKIM fail and where to send reports. Start with p=none, then move to quarantine/reject once aligned.
Publish a rua address so you can see spoofing and misalignment before you tighten policy.
Operator playbook
How we set up domains for cold outbound
- 01
Separate brand from cold volume
Never blast cold from your primary corporate domain. Use dedicated sending domains so customer and investor mail stay clean.
- 02
Authenticate every sending domain
SPF + DKIM + DMARC on each cold domain before warmup. This checker is the five-minute sanity pass.
- 03
Warm, then send
Authentication without warmup still fails. Use the Warmup Calculator to plan the ramp, then graduate to real ICP volume.
A green score is necessary — not sufficient
Passing DNS does not mean Google or Microsoft will love your cold volume tomorrow. Reputation still needs warmup, clean lists, and restrained content. Use this checker as the gate before ramp — then operate the rest of the system.
How it works
Three steps. No signup. No waiting.
- Step 01
Enter your domain
Just the domain — no @, no protocol. We look up the live DNS records ourselves.
- Step 02
We resolve your real records
Server-side DNS query against SPF, DKIM (default selector), DMARC, and MX. Read-only.
- Step 03
Fix what's broken
Each missing or mis-configured record gets a status, the raw value we found, and a copy-paste fix.
Frequently asked
Quick answers, no fluff.
- Why does DKIM show inconclusive on a working domain?
- DKIM uses a selector chosen by your email provider. We probe common selectors but cannot guess every custom one. If mail already authenticates in your ESP, a miss here is often just selector mismatch — not a broken domain.
- Will this fix my deliverability?
- It tells you what is missing or misconfigured. Adding records is usually a short DNS edit. Reputation, warmup, and list quality are separate — this is the identity gate.
- Is the lookup logged?
- No. We perform a read-only DNS query and return the result to your browser without keeping a lookup history for marketing.
- Should I put cold email on my primary company domain?
- No. Use dedicated sending domains for cold volume so customer and investor mail on @company.com stay protected if outbound reputation dips.
- What DMARC policy should I start with?
- Most teams start with p=none plus reporting (rua) to see alignment failures, then move to quarantine/reject once SPF and DKIM are solid. Jumping straight to reject without monitoring can break legitimate mail.
- Does a high score mean I am ready to send cold volume?
- It means authentication looks healthy. You still need warmup, clean lists, and restrained content before full volume. Pair this with the Warmup Calculator.
- Can I check a competitor’s domain?
- Yes — DNS is public. Use it to learn how serious senders configure mail, not to copy their cold domains wholesale.
Want us to stand up and warm your sending domains?
Free outreach audit — DNS, warmup plan, and first-campaign readiness in one pass.
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