Email Validator
Validate email address format and domain.
How to use Email Validator
Enter Your Email Address
Click the input field labeled 'Email Address' and type or paste the email you want to validate. You can enter a single email or multiple addresses separated by commas or newlines.
Click the Validate Button
Press the blue 'Validate Email' button below the input field. The tool will instantly process your email and begin checking the format and domain validity.
Review Validation Results
View results in the 'Results' panel on the right. Each email shows a green checkmark for valid addresses or red X for invalid. Hover over any result to see specific issues like invalid format, non-existent domain, or syntax errors.
Export or Copy Results
Click 'Copy Results' to copy all validation data to your clipboard, or select 'Export as CSV' to download results for use in spreadsheets or email applications.
Related Tools
Email validator online: check if an email address is valid instantly
Email validator online: check if an email address is valid instantly
Need to know if an email address is real before sending? ToolHQ's Email Validator checks the format, domain, and mail server of any email address to tell you whether it's valid and deliverable. Free, no account required.
ToolHQ's Email Validator is a free online tool that checks email addresses for format correctness, domain existence, and mail server (MX record) configuration, giving you a clear valid or invalid verdict without sending a test email.
Sending emails to invalid addresses causes bounces. High bounce rates damage your sender reputation with email providers like Gmail and Outlook, reducing deliverability for your entire domain. Validating addresses before sending, whether for a single contact or a full mailing list, prevents this problem before it starts.
Key Takeaways
- Validates email format, domain existence, and MX record configuration
- Gives a clear valid/invalid verdict without sending a test email
- Only the domain part of the email is queried for verification
- Helps prevent email bounces and protects sender reputation
- Free with no account required
What email validation actually checks
Email validation is not a single check. It is a layered process that can verify different aspects of an email address depending on how deep the validation goes.
Syntax check: The first layer validates that the email address conforms to the correct format as defined in RFC 5322. A valid email address has a local part (before the @), an @ symbol, and a domain part (after the @). Common syntax errors include missing @, double @, spaces, or invalid characters.
Valid example: user@example.com
Invalid examples: user@, @example.com, user@ example.com, user..name@example.com
Domain existence check: The second layer queries the DNS system to verify that the domain (the part after @) actually exists as a registered domain. user@fake-domain-that-doesnt-exist.com will fail this check because the domain is not registered.
MX record check: The third layer checks whether the domain has mail exchange (MX) records configured in DNS. MX records tell the internet which mail servers accept email for a domain. A domain without MX records cannot receive email, regardless of whether the domain itself is registered.
SMTP verification: Some advanced validators attempt an SMTP handshake with the mail server to verify that the specific mailbox exists on that server. Many mail servers block this to prevent spam, making it unreliable.
ToolHQ's Email Validator performs syntax, domain, and MX record checks. Only the domain part of the email address you enter is queried for verification. The local part (the username before the @) is not sent to any server.
Why email validation matters
Invalid email addresses are a practical problem with measurable consequences.
Bounce rates and sender reputation: Email service providers (ESPs) like Mailchimp, SendGrid, and HubSpot track your bounce rate. Consistently sending to invalid addresses raises your bounce rate above acceptable thresholds (typically 2%), which can result in account suspension. ESPs use bounce rates as a signal of list quality.
Wasted sends: If you pay per-email with your ESP, sending to invalid addresses wastes money directly. More practically, it wastes the time spent crafting and personalizing emails that will never be read.
Data quality in CRMs: Email addresses entered into CRM systems manually or through web forms are prone to typos. Validating at the point of entry catches errors before they propagate through your system.
Contact form spam: Web forms that accept email addresses without validation receive large volumes of invalid, fake, or disposable email addresses from bots. Validation at submission reduces noise.
According to research cited across email marketing literature, email lists decay at approximately 20-25% per year as people change jobs, domains close, and addresses become inactive. Starting with clean, validated data slows this degradation.
When to use an email validator
Before a cold outreach campaign: If you're emailing a list sourced from a database, event signups, or public directories, validate the list before sending. Even a 5% invalid address rate on a 1,000-contact list means 50 bounces and potential sender reputation damage.
When importing contacts into a CRM: Running incoming contact lists through validation before import keeps your CRM data clean from the start.
Checking a single contact: When you're not sure whether an email address you have for a specific person is still valid before sending an important message, a quick validation check tells you whether to look for an alternative address first.
Form field validation: Before sending emails to addresses collected through your web forms, validating each address on submission or batch-validating before sending reduces bounce rates.
Mini-story: In September 2025, Lena, who managed marketing at a software company in Stockholm, inherited an email list of 8,500 contacts from a trade show attendance list that was two years old. Before running a product launch campaign, she validated the list using an email validator. Of the 8,500 addresses, 1,340 came back invalid (missing MX records or failed syntax). She removed those from the send list. The campaign sent to 7,160 addresses and achieved a 0.4% bounce rate, well within her ESP's acceptable threshold. Without validation, she estimated the bounce rate would have been around 15%, which would have triggered a send limit review on her account.
Validate an email address now, free, no account needed
How to use ToolHQ's email validator: step by step
Validation takes seconds per address.
- Open the tool. Go to https://www.toolhq.app/tools/email-validator. No login required.
- Enter the email address. Type or paste the address you want to validate.
- Run validation. The tool checks syntax, domain existence, and MX record configuration.
- Read the result. The tool returns a verdict (valid/invalid) and details about which checks passed or failed.
- Act on the result. If invalid, decide whether to seek an alternative address or remove the contact from your send list.
Understanding common validation results
| Result | What it means | What to do |
|---|---|---|
| Valid | Syntax correct, domain exists, MX records found | Safe to send |
| Invalid syntax | Missing @, spaces, or malformed format | Confirm the address and correct the typo |
| Domain not found | Domain does not exist or has been deleted | Address is unreachable; seek alternative |
| No MX records | Domain registered but not configured for email | Address cannot receive email |
| Unverifiable | MX exists but SMTP check was blocked | May be valid; proceed with caution |
Mini-story: James, a recruiter in Dublin, was building his outreach list for a senior engineering hiring campaign in November 2025. He found potential candidates through professional networks and noted their email addresses. Before reaching out, he ran each address through ToolHQ's Email Validator. Three addresses showed "domain not found" (companies that had since closed or rebranded). Two showed "no MX records" (personal domains with no email configured). He skipped those and found alternative contacts, saving himself five cold emails that would have bounced. His campaign achieved a 0.2% bounce rate.
For related tools, ToolHQ's DNS Lookup lets you inspect MX records and other DNS configuration directly. The What Is My IP tool and other network tools are in ToolHQ's network category.
Frequently asked questions
Does the email validator send a test email?
No. The tool checks syntax, domain DNS records, and MX records without sending any email to the address.
Is the email address I enter private?
Only the domain part (after the @) is queried for DNS and MX record lookup. The username part is not transmitted to any external server.
Can it verify that a specific mailbox exists?
The tool checks MX records, confirming the domain can receive email. Verifying a specific mailbox requires an SMTP-level check, which many mail servers block to prevent abuse.
Why might a valid-looking email show as invalid?
Common reasons: the domain is registered but has no MX records configured (cannot receive email), the domain has expired, or the email address has a syntax error that's easy to miss (doubled dot, missing TLD).
What are disposable email addresses and can the validator detect them?
Disposable email addresses (also called temp-mail or throwaway addresses) are provided by services like Guerrilla Mail, Mailinator, and Temp-Mail. They create temporary inboxes at domains like @mailinator.com or @guerrillamail.com. These addresses are technically valid: correct syntax, real domain, real MX records. A basic syntax and MX check will mark them as valid. More advanced validators maintain blocklists of known disposable email domains to flag them separately. Disposable addresses are common in form submissions where users want to avoid providing a real email. If you run a form or mailing list and want to exclude throwaway addresses, use a validator that specifically checks against disposable domain lists.
What is a catch-all email address?
A catch-all (or accept-all) email configuration means the mail server accepts emails sent to any address at that domain, even addresses that don't correspond to a real user. anything@company.com would pass MX checks and even an SMTP handshake because the server accepts all incoming mail regardless of the local part. A validator can confirm the domain accepts email, but cannot determine if the specific mailbox is a real user's account when catch-all is enabled. The result is typically reported as "unverifiable" or "accept-all." Treat these addresses as uncertain.
Can I validate a list of emails at once?
ToolHQ's Email Validator checks one address at a time. For bulk validation of large lists, dedicated email list cleaning services provide batch processing.
Conclusion: the short version
Sending emails to invalid addresses causes bounces, damages your sender reputation, and wastes your time. ToolHQ's Email Validator checks syntax, domain existence, and MX records to tell you whether an email address is deliverable before you send. Free, no account, results in seconds.
Validate before you send. It's the easiest way to protect your delivery rate.
Validate an email address now, free, instant, no account needed
For related network tools, use DNS Lookup to inspect domain records directly. See all network tools in ToolHQ's network section.