What is Valid Email Checker?

Valid Email Checker is a tool you run before you send. You feed it a single email or a full list, and we tell you which addresses are real, which will bounce, and which ones look risky in ways that are not obvious from the outside.

The short version of why this matters: every bounced email chips away at your sender reputation. Once Gmail or Outlook decides you are sending to too many dead addresses, your future emails (even the ones to real people) start landing in spam. Verifying first prevents the problem instead of recovering from it.

What runs under the hood

Every verification runs through 11 distinct checks:

1. Syntax validation — is the address formatted correctly?
2. Domain DNS lookup — does the domain actually exist?
3. MX record check — is the domain configured to receive mail?
4. SMTP handshake — can we even reach the recipient mail server?
5. Mailbox existence — does the specific mailbox exist? We use SMTP RCPT TO to ask without ever sending a real message.
6. Catch-all detection — does the server accept anything on the domain regardless of mailbox existence?
7. Disposable provider check — throwaway service like Mailinator, 10MinuteMail, or Guerrilla Mail?
8. Role-account detection — info@, support@, sales@, admin@, and similar function-based addresses.
9. Spam-trap detection — known honeypot used to catch senders with poor list hygiene?
10. Inbox-full detection — mailbox exists but the server says it is over quota.
11. Disabled-account detection — account existed at some point but has been deactivated by the provider.

For the full mechanics, see how verification works.

Where it fits in your workflow

Two common patterns. The first is bulk cleanup: you upload a CSV or TXT with your subscribers, we run them through the verification engine, you get back a clean list with each address tagged as Safe, Invalid, Disposable, Catch-All, Role Account, Spam Trap, Disabled, Inbox Full, or Unknown.

The second is real-time verification through our API or through one of the 17 native integrations (Mailchimp, HubSpot, Klaviyo, ActiveCampaign, Brevo, ConvertKit, Mailgun, MailerLite, GetResponse, Constant Contact, SendGrid, Drip, AWeber, Campaign Monitor, Elastic Email, Mailjet, Moosend). A new contact lands in your CRM, we verify it in the background, bad addresses get tagged or unsubscribed automatically.