Email syntax validator
Check one email address for practical syntax errors, likely typos, disposable-domain risk and role-based local parts, and get a verdict plus a low/medium/high risk grade. Runs offline with no DNS or SMTP probes.
About this tool
Validate one email address before it enters a signup form, CSV import or allowlist. The tool combines practical RFC 5321/5322 syntax checking (including likely-typo suggestions) with a bundled disposable-domain list, then adds a role-address check for shared local parts such as admin, info, sales, support, postmaster and abuse.
Every run returns a pass/fail verdict plus a low/medium/high risk grade. Bad syntax or a disposable domain is a fail at high risk; a deliverable address that is still worth a human look — a role alias, or a likely domain typo like [email protected] — passes at medium risk.
Worked example: [email protected] with both checks enabled returns fail: [email protected] (syntax: valid, disposable: yes, role_based: yes, risk: high) in summary format — the syntax is fine, but the domain is a known throwaway inbox and the local part is a role alias.
Pick report for a labelled multiline breakdown, summary for a single line, or json for machine-readable fields (valid, disposable, role_based, risk, verdict, errors, warnings, suggestion). Turning a check off reports that category as not checked rather than as a clean result.
This is an offline syntax and risk check. It does not perform DNS, MX, SMTP or mailbox-existence probes, so a pass verdict means the address is well-formed and not on the bundled risk lists, not that the mailbox can receive mail. It validates one address at a time; use a list cleaner for bulk workflows.
FAQ
Does this contact the domain's mail server?
No. The tool is intentionally offline and deterministic — the same address always produces the same result. It checks practical syntax rules, a bundled disposable-domain list and optional role-address patterns without any DNS, MX or SMTP network call, so nothing you paste leaves the page.
Why are role-based addresses flagged?
Addresses like info@, support@, admin@ and postmaster@ usually reach a team or an automated queue rather than one person. They are perfectly deliverable, so they still get a pass verdict — but they are graded medium risk because many marketing, onboarding and abuse-prevention workflows want to review or block them. no_reply@ is matched too: underscores are folded to hyphens before the lookup.
Is the disposable-domain list exhaustive?
No. Disposable mail providers add domains constantly. The bundled list covers the common throwaway services and their alias domains and subdomains, plus a conservative throwaway-keyword heuristic — it is a fast, high-precision signal, not a registry. A Disposable: no result means "not on the known list", so pair it with your own policy for high-risk signups.
What is the difference between the verdict and the risk grade?
The verdict answers "should this be accepted at all": it is fail only when the syntax is invalid or the domain is disposable. The risk grade adds nuance for everything that still passes — medium for a role alias or a likely domain typo, low for an ordinary personal address. Cosmetic notes, such as the address having had surrounding whitespace that was trimmed, appear under warnings but do not raise the risk grade.
Developer & Automation Access
Run it from the terminal
Same engine as this page, headless — via the gizza CLI:
gizza tool email-syntax-validator "Ada Lovelace <[email protected]>"New to the CLI? Get gizza →
Open it by URL
Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:
https://gizza.ai/tools/email-syntax-validator/?email=Ada%20Lovelace%20%3Cada%40example.com%3E&check_disposable=true&check_role=true&format=reportMachine-readable descriptor: tool.json — title + parameters JSON Schema for agents.