Free tool — 10 checks per day from this page. Need to clean your list too? Create a free account.
§ WHY IT MATTERS
Bad DNS sinks your inbox rate.
6
DNS checks run on every domain (MX, SPF, DMARC, DKIM, PTR, RBL)
~3s
to a full report — all lookups run in parallel
0
logins, installs, or emails required to run a check
§ WHAT WE CHECK
Six records, one verdict.
MX records
Confirms your domain can actually receive mail and that mail hosts resolve — with a nudge if there's no backup MX.
SPF
Validates your sender policy, counts DNS lookups against the RFC limit of 10, and flags weak ?all / +all endings.
DMARC
Reads your anti-spoofing policy and warns when p=none leaves your domain open to impersonation.
DKIM
Probes ~20 common selectors to find your signing key, so receivers can verify your mail wasn't tampered with.
PTR / reverse DNS
Checks forward-confirmed reverse DNS on your sending IP — a quiet but real deliverability factor.
Blacklists (RBL)
Looks up your mail IP against reputable real-time blacklists so you catch reputation problems early.
§ THE PRIMER
Why DNS decides your deliverability
Before a mailbox provider like Gmail or Outlook decides where to put your message, it asks DNS a few hard questions. Who is allowed to send for this domain? (SPF). Was this message signed and unaltered? (DKIM). What should I do with mail that fails? (DMARC). Get any of these wrong and even a perfectly written email can land in spam — or vanish entirely.
The classic failure isn't a missing record; it's a subtly broken one. An SPF record that quietly exceeds 10 DNS lookups fails with a permerror. A DMARC policy stuck on p=none monitors spoofing but never blocks it. A sending IP with no reverse DNS gets throttled. None of these throw an obvious error — they just slowly erode your inbox placement.
This checker reads all six signals in one pass and grades them the way a receiver would, then hands you the specific change to make for each warning. Fix the reds, clear the ambers, and you've removed the DNS reasons a provider might distrust you.
DNS is one half of deliverability; your list is the other. Once your records earn an A, verify your recipients before each send so you're not pairing a trusted domain with dead addresses and spam traps.
§ FAQ
DNS health FAQ
Everything about the checks we run, how to read your score, and what to fix first.
Still have questions? Contact us§ PROTECT YOUR DELIVERABILITY
Trusted domain. Clean list.
Fix your DNS here, then verify your recipients before you send. Free plan includes 50 verifications a month — no card required.
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