Free email & DNS tools
Seven tools for diagnosing email deliverability. Every one runs real DNS lookups, explains what it found in plain English, and tells you honestly where its certainty ends.
Email Checker
Validate any email address
Check syntax, look up real MX records, and detect disposable, role-based and free-provider addresses.
Validate emailMX Lookup
Find a domain's mail servers
See which servers accept mail for a domain, in priority order, and which provider runs them.
Look up MX recordsSPF Checker
Count your DNS lookups
Expand the whole include tree and see how many of the 10 permitted DNS lookups you actually use.
Check SPF recordsDKIM Checker
Find selectors, check key strength
Probe 45 common selectors, read RSA key sizes, and catch revoked or testing-mode keys.
Inspect DKIM keysDMARC Checker
See if spoofing is actually blocked
Inspect the policy, reporting addresses and alignment, and catch the typos that silently disable it.
Verify DMARC policyDisposable Checker
Detect throwaway domains
Check a domain against 159,000+ known temp-mail providers — and tell disposable apart from merely free.
Detect disposable emailsBlacklist Checker
See if you are blocked
Check an IP or domain against the DNS blocklists receivers actually consult, with delisting links.
Check blacklist statusWhere these tools stop
These free tools use DNS lookups. Here's what DNS can and can't tell you.
What DNS can do
Tell you whether a domain accepts mail, how its outbound mail is authenticated, and whether it is a throwaway provider. That covers most deliverability problems.
What DNS cannot do
Tell you whether one specific mailbox exists. Every address at a domain shares the same MX records – [email protected] and [email protected] look identical from the outside. That requires an SMTP connection to the mail server directly.
Why we don't probe mailboxes here
A public, keyless tool that probes mailboxes becomes a mailbox-enumeration service. Mail providers blocklist IPs that do it – which would ruin deliverability for paying customers. These tools say "the domain accepts mail" and stop there.
Need mailbox-level answers?
The MailValid API provides SMTP-confirmed verification with catch-all detection, one address at a time or 10,000 in a batch.
Verify real mailboxes, in bulk
95%+ accuracy, 5–10× cheaper than ZeroBounce, and credits that never expire. Start with 100 free credits – no credit card required.