Email Validator
Use this free Email Validator to quickly get accurate results in seconds, free and instantly offline with no signup required ever, trusted by professionals in Austin, Chicago, Miami, Denver, Seattle, and New York for reliable daily use without accounts, subscriptions, limits, or delays on any device for everyday personal and business workflows daily.
Check email syntax with this email validator, verifying the local part, domain, format, and length rules for valid email addresses.
Calculator Inputs
About Email Validator
Use this free Email Validator to quickly get accurate results in seconds, free and instantly offline with no signup required ever, trusted by professionals in Austin, Chicago, Miami, Denver, Seattle, and New York for reliable daily use without accounts, subscriptions, limits, or delays on any device for everyday personal and business workflows daily.
Email Validator — RFC 5322 Syntax and Domain Verification: This tool validates email addresses against the RFC 5322 standard, which governs the syntax of email addresses used across the internet. It checks the local part (before the @) for allowed characters, verifies exactly one @ symbol exists, and confirms the domain has at least one dot for a top-level domain. Multiple addresses can be validated at once, one per line. The entire validation runs instantly offline with no signup required ever, completing in seconds in your browser.
The local part (everything before @) can contain letters, digits, and the special characters . ! # $ % & ' * + / = ? ^ _ ` { | } ~ — these are the characters permitted by RFC 5322 without quoting. The local part must be 64 characters or fewer. The domain part is checked for valid hostname format: alphanumeric characters and hyphens, with at least one dot separating the domain from the TLD when the domain check option is enabled.
The validator processes addresses in batch, producing a report for each line that shows VALID or INVALID along with the specific problem found. Common issues flagged include spaces in the address, missing @ symbols, local parts exceeding 64 characters, and domains without a TLD (like user@localhost). A Chicago developer building a $50,000 signup flow on 09/15/2026 can paste hundreds of test addresses and see results instantly.
Important distinction: syntax validity does not prove a mailbox exists. An address like valid@example.com may pass syntax checks but the domain might not exist, the mailbox might not be configured, or it could be a disposable address. Only a delivery attempt (SMTP handshake) can confirm an actual mailbox. This tool catches formatting errors before they cause delivery failures.
All validation happens locally — no addresses are sent to any server, no DNS queries are made, and no data is stored. Whether you are an Austin marketing director cleaning a $20,000 campaign list on 08/20/2026, a Miami nonprofit verifying $15,000 donor emails, or a New York agency auditing $30,000 outreach contacts, the tool works at $0 cost with complete privacy.
Where it is used
An Austin marketing team cleaning a 10,000-subscriber mailing list before a $20,000 campaign, a Chicago SaaS developer validating form inputs on a $50,000 signup flow, a Miami nonprofit verifying donor emails for a $15,000 appeal, a Denver HR department checking applicant emails for 500 résumés, a Seattle e-commerce store validating customer emails for a $100,000 product launch, and a New York agency auditing 3,000 contact records for a $30,000 outreach.
How to use the Email Validator
- Email address(es) to validate — enter the value (One or more email addresses, one per line.).
- Check that the domain looks like a real domain (has TLD) — enter the value.
- Calculate — press the Calculate button to see the result instantly above.
Examples
Batch validation
Missing TLD
Multiple @ signs
Frequently Asked Questions
- Does VALID mean the inbox exists?
- No — it only confirms the address is syntactically plausible. A valid format does not prove the domain is registered or the mailbox is configured. Only a delivery attempt can confirm that.
- Are international (IDN) domains supported?
- Basic Unicode domains may fail this ASCII-only regex. For IDN addresses, convert the domain to punycode (e.g. xn--...) before validation for accurate results.
- What is the difference between local part and domain validation?
- The local part is checked for allowed characters and length (max 64). The domain is checked for valid hostname format and optionally for the presence of a TLD when the domain check is enabled.
- Can this catch disposable email addresses?
- This tool checks syntax only. Detecting disposable domains (like mailinator.com or guerrillamail.com) requires a domain blocklist, which is a separate validation layer.
- How many addresses can I check at once?
- There is no hard limit — paste as many as you like, one per line. The tool processes them all in your browser. For very large lists (10,000+), processing may take a few seconds.
- Why is a single @ symbol required?
- RFC 5322 specifies exactly one @ in a valid email address. Multiple @ signs (like user@@domain.com) or missing @ signs (like userdomain.com) are always invalid.