Email syntax validator
Validate the format of any email address
Enter an email address to run RFC-aware syntax checks: the @ structure, mailbox length and characters, dot placement, and a well-formed domain. The tool also confirms the domain has MX records so you know whether mail could even be delivered.
Validate an email address
Runs RFC-aware syntax checks on the address, then verifies the domain has MX records. Syntax validity does not guarantee the mailbox exists.
Syntax is only the first gate
A perfectly formatted address can still bounce. Verifly checks the mailbox itself for deliverability, disposable domains, role accounts, and catch-all behavior.
Verify a whole list with 100 free creditsWhat syntax validation catches
Syntax validation catches the format errors that cause an immediate rejection: a missing or doubled @, an empty or over-long mailbox, illegal characters, dots in the wrong place, spaces, and domains with no real top-level domain.
These are the typos that creep into signup forms and pasted lists, and they bounce 100% of the time.
What syntax validation cannot catch
A valid format does not mean a real, reachable mailbox. ceo@example.com can be perfectly formatted and still not exist.
That is why this tool also checks for MX records, and why a full verification, which probes the mailbox itself, is the only way to confirm deliverability.
What the RFC actually allows
Email syntax is defined by RFC 5322 and related standards, and the rules are broader than most people expect. The local part (before the @) permits dots, plus-tags like name+news@, and even quoted strings; the domain must be a valid hostname. A well-built validator applies these real rules instead of an overly strict regex that wrongly rejects valid addresses.
This tool breaks the address into individual checks so you can see exactly which rule failed: the @ structure, mailbox length and characters, dot placement, and a well-formed domain with a real top-level domain.
Syntax is necessary but not sufficient
A perfectly formatted address can still be undeliverable. ceo@example.com is valid syntax yet may not exist. That is why the validator also confirms the domain has MX records, which shows the domain is at least capable of receiving mail, one step beyond format alone.
The only way to confirm a specific mailbox exists is to verify it against the mail server. For that final step, run the address through the email risk checker or verify in bulk with the Verifly API.
Where syntax validation pays off
Client-side syntax validation belongs on every signup and checkout form. It catches the typos that bounce 100% of the time, missing @ signs, trailing spaces, .con instead of .com, before they ever enter your database, saving you the cost of verifying and then discarding them later.
Pair it with a typo fixer to suggest corrections in real time, and reserve paid mailbox verification for addresses that already pass format and MX checks. This layering keeps both your list and your verification spend lean.
Frequently asked questions
Does a valid syntax mean the email works?
No. Syntax validation only confirms the address is correctly formatted and that the domain has mail servers. It cannot tell you whether the specific mailbox exists or accepts mail. Confirming that requires verifying the address against the mail server.
Are plus-tags like name+news@gmail.com valid?
Yes. The plus sign and the text after it are allowed in the local part under RFC rules, and providers like Gmail use them as sub-addresses that still deliver to the base mailbox. A correct validator accepts them rather than flagging them as errors.
Why does the tool also check MX records?
MX records reveal whether the domain can receive mail at all. An address can be flawless in format but sit on a domain with no mail servers, making it undeliverable. Checking MX adds a deliverability signal that pure format checking misses.
Should I validate email format on my signup form?
Yes. Running syntax validation in the browser catches obvious typos before they reach your database, reducing bounces and cleaning your list at the source. It is cheap, instant, and prevents you from paying to verify addresses that were never going to work.
Why do some validators reject addresses that are actually valid?
Many rely on a naive regular expression that does not implement the full RFC, so they wrongly reject legal addresses with dots, plus-tags, or unusual but permitted characters. Using rule-based checks that follow the standard avoids turning away real users.
How do I validate an entire list of addresses?
This tool validates one address at a time. To validate and verify thousands, use the Verifly API with a vf_ Bearer key: GET /verify?email= returns syntax and deliverability signals along with disposable, role, and catch-all flags.
Embed this email syntax validator on your site
Drop this snippet into any page to add a live, self-contained checker. It links back to Verifly, costs nothing, and needs no API key.
<iframe src="https://verifly.email/tools/embed/email-syntax-validator" width="100%" height="680" style="border:0;border-radius:12px;max-width:760px" title="Email Syntax Validator by Verifly" loading="lazy"></iframe> <p style="font:13px sans-serif"> Free <a href="https://verifly.email/tools/email-syntax-validator">Email Syntax Validator</a> by <a href="https://verifly.email">Verifly email verification</a> </p>
Related tools
Verify a whole list, not one address at a time
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