Email Validator
Validate email address format and domain
How to use Email Validator
Validate email address format and check domain existence. Bulk validation supported. Free online email validator tool.
What is email validation used for?
Invalid email addresses in your database cause bounced emails, damage sender reputation, inflate subscriber counts, and waste marketing spend. Validating at point of entry — in forms and imports — is far cheaper than cleaning up later.
- Form validation: Catch typos and formatting errors at signup — "user@gmial.com" instead of "user@gmail.com". Immediate feedback prevents users from registering with an unreachable address.
- List cleaning: Before an email campaign, validate the entire list. Sending to invalid addresses increases bounce rate, which ISPs use to classify senders as spammers. A bounce rate above 2% can get your domain blacklisted.
- CRM data quality: Validate email addresses imported from spreadsheets, business card scans, or legacy databases before entering them into your CRM.
- Developer testing: Verify that your form's validation logic correctly rejects malformed addresses and accepts valid-but-unusual ones (user+tag@sub.domain.co.uk).
- Bulk import screening: Before importing a CSV of contacts, run the email column through validation to identify and quarantine invalid entries.
Validation levels: Syntax validation checks the format. Domain validation verifies the domain exists and has MX records. SMTP validation (not done here for privacy) checks if the specific mailbox accepts mail. Each level catches more invalid addresses but requires more resources.
Frequently Asked Questions
What makes an email address valid?
A valid email has a local part, @, and domain: local@domain.tld. The local part allows letters, digits, and .!#$%&'*+/=?^_{|}~- (but not starting/ending with dots or consecutive dots). The domain must be a valid hostname with at least one dot. Technically valid but unusual: user+tag@example.co.uk, 123@numbers.com, user@[192.168.1.1].
Can I validate emails without sending a test email?
Syntax and domain validation can be done without sending. True deliverability validation requires an SMTP check — connecting to the mail server to verify the mailbox exists. This is intrusive, slow, and some servers reject or mislead such checks. For most purposes, syntax + domain (MX record) validation is sufficient.
Why do email validators sometimes fail on valid addresses?
Email syntax rules (RFC 5321/5322) allow unusual characters that validators sometimes reject — like quoted strings ('user name'@domain.com) or uncommon domains (.museum, .travel). Real-world validators balance strict RFC compliance against practical usability. Rejecting clearly valid but unusual addresses is preferable to accepting clearly invalid ones.
What is email disposable address detection?
Disposable email services (Mailinator, Guerrilla Mail, 10minutemail) provide temporary inboxes that expire. Some validators maintain blocklists of disposable domain names and reject signups from them. This helps prevent abuse of free trials and spam registrations, but may occasionally block legitimate users.
What is the difference between hard bounce and soft bounce?
A hard bounce means the email address permanently does not exist or is invalid — the domain does not exist, or the mailbox is permanently closed. Remove hard bounces immediately. A soft bounce is a temporary delivery failure — the mailbox is full, the server is temporarily down. Retry soft bounces up to 3 times before removing.
Syntax validation vs domain validation vs SMTP validation vs email verification service
Syntax validation (regex-based) checks format — fast, free, catches typos. Domain validation checks MX records — confirms the domain can receive email. SMTP validation tests if the specific mailbox accepts mail — most accurate but slow and blocked by many servers. Commercial verification services (ZeroBounce, NeverBounce, Hunter.io) combine all three plus proprietary databases of known-invalid addresses and role accounts (info@, admin@) — paid, most thorough. For small forms: syntax validation. For large campaigns: commercial service.