How email verification works
Syntax, DNS, MX, and SMTP — what a verifier checks and what it does not do (no message delivered to the inbox).
Email verification is a technical check of an address, not a test message delivered to the recipient inbox. We assess whether the address makes sense and whether the mail infrastructure looks active — before you add a lead to CRM or send a campaign.
What we check step by step
- Syntax — valid format (RFC) and common typos.
- DNS and MX — the domain exists and accepts mail.
- SMTP — the recipient server responds to a handshake without message content.
- Heuristics — disposable, catch-all, role-based (e.g. info@), free vs corporate.
No single layer is 100% deterministic. Mail servers sometimes return ambiguous responses (greylisting, catch-all).
Statuses you will see
- Valid — likely active; safe to send in most scenarios.
- Invalid — no MX, dead domain, or mailbox that does not exist.
- Risky — catch-all, disposable, or role address; business decision required.
- Unknown — inconclusive server response; retry verification.
When to verify
- Before a campaign — remove hard bounces before your ESP counts bounce rate.
- At signup — real-time API keeps your database clean from day one.
- Before CRM import — one-off audit of lists from multiple sources.
Next steps
With EmailVerifier you can check a single address or upload a CSV list. One verified address = one credit, pay-as-you-go, credits never expire.