Email Validator
Check email addresses for format, domain, deliverability, and quality score
What we check
Free Email Validator — Check Email Addresses for Format, Deliverability & Quality
Sending an email to an invalid address isn't just wasted effort — it can hurt your sender reputation, inflate your bounce rate, and even get your domain flagged by email service providers. The OmniWebKit Email Validator helps you catch bad addresses before they cause problems. It works entirely in your browser, requires no sign-up, and gives you a detailed quality report for every email address you check.
Whether you're cleaning up a marketing list, verifying user sign-ups, or just confirming a single address, this tool covers all the important checks: format compliance, domain structure, disposable email detection, role-based address flagging, and a 0–100% quality score that tells you at a glance how trustworthy each address is.
The Bulk Check mode lets you validate up to hundreds of addresses at once, filter results by valid/invalid, and export everything as a CSV file with one click. Real-time validation in Single mode shows you the result as you type — no button press needed.
Every Check Explained
The validator runs ten distinct checks on each address and combines the results into a quality score. Here's exactly what each check looks for:
RFC 5322 Format Compliance
The most important check. RFC 5322 is the internet standard that defines what a valid email address looks like. An address must have exactly one @ symbol, with a local part before it and a domain after it. The local part can contain letters, numbers, and certain special characters. The domain must follow specific hostname rules. Many validators stop here — ours goes much further.
Valid Top-Level Domain (TLD)
The TLD is the last part of the domain — .com, .org, .io, .uk, and so on. We verify that a TLD exists and is at least two characters long. An address like user@domain will fail this check because there is no TLD.
Local Part Length
The local part (everything before the @) must be between 1 and 64 characters according to internet standards. Addresses shorter or longer than this range will not work reliably across all email systems.
No Consecutive or Edge Dots
A double dot (..) in the local part makes an address invalid under RFC 5321 and RFC 5322. Similarly, the local part cannot start or end with a dot. These rules exist because mail servers use dots as separators and treat these patterns as formatting errors.
Disposable Email Detection
We check the domain against a database of 40+ known disposable and temporary email providers, including Mailinator, Guerrilla Mail, YOPmail, 10 Minute Mail, Temp-Mail, and many others. Disposable addresses are often used to bypass registration requirements and are unlikely to belong to genuine users.
Role-Based Address Detection
Addresses like admin@, info@, support@, noreply@, and contact@ are role-based — they go to a team or mailbox rather than an individual. These addresses are flagged with a warning because they often have lower engagement rates and may not work for transactional emails.
Recognized Provider Check
We check whether the domain belongs to a well-known consumer email provider like Gmail, Outlook, Yahoo, iCloud, ProtonMail, and others. If the domain is not recognized, it may be a business or custom domain — which is still valid, just noted as unverified.
Quality Score (0–100%)
All check results are combined into a percentage score. 80% or above indicates a high-quality, deliverable address. 50–79% suggests potential issues worth reviewing. Below 50% means the address failed critical checks and is unlikely to be valid.
Why Email Validation Matters for Marketing and Deliverability
Your email list is only as good as the addresses in it. A dirty list with invalid addresses hurts you in several ways that compound over time.
Bounce rate
When emails bounce — because the address doesn't exist or the mailbox is full — email service providers like Mailchimp, Klaviyo, and SendGrid track those bounces. Too many hard bounces (permanent failures) and your sending account can be suspended.
Sender reputation
Internet Service Providers (ISPs) and spam filters score every sender based on bounce rates, spam complaints, and engagement. A poor sender score means your emails start going to the spam folder — not just for the bad addresses, but for everyone on your list.
Cost inefficiency
Most email platforms charge by subscriber count or email volume. Paying to send emails to addresses that will never deliver is pure waste. Cleaning your list before importing it saves money.
Analytics accuracy
Invalid addresses skew your open rate, click rate, and conversion metrics. A clean list gives you accurate data to make better decisions.
Regular email validation — before sending, before importing, and at the point of sign-up — is one of the most effective things you can do to protect your sender reputation and keep your list healthy.