// Guide
How Email Verification Works: Syntax, MX, and SMTP
Last verified · 2026-06-24
The short answer
Email verification runs an address through layered checks: syntax validation (is it well-formed), MX lookup (does the domain accept mail), SMTP probing (does the mailbox exist), plus catch-all, role-account, and disposable-domain detection. Each stage filters out addresses that would bounce. Verifying before you send keeps bounce rates low and protects sender reputation. Trackyr verifies emails at pull time for 1 credit each.
The verification pipeline
Verification isn't a single test. It's a sequence of checks, each catching a different failure mode. An address has to pass every stage to be considered deliverable.
- Syntax: confirm the address is structurally valid.
- MX lookup: confirm the domain has mail servers that accept email.
- SMTP probe: ask the mail server whether the specific mailbox exists.
- Catch-all detection: flag domains that accept everything (unverifiable).
- Role and disposable checks: flag info@, sales@, and throwaway domains.
Why each stage matters
| Stage | Catches |
|---|---|
| Syntax | Typos and malformed addresses |
| MX | Dead or non-mail domains |
| SMTP | Nonexistent mailboxes |
| Catch-all | Domains you can't confirm |
| Disposable | Throwaway addresses that won't convert |
The catch-all problem
Some domains accept mail to any address, so the SMTP probe can't confirm whether a specific mailbox exists. These come back as 'unknown' or 'accept-all'. Treat them as risky, not safe, and weight them accordingly in your send strategy.
Verify at the source
The cheapest place to verify is the moment you acquire the contact. Trackyr verifies emails at pull time (1 credit each) and re-verifies continuously, so addresses don't silently rot between when you pull them and when you send.
More on this topic: Verification →
// Common questions
Answered.
What does an 'accept-all' or 'catch-all' result mean?+
The domain accepts mail to any address, so the verifier can't confirm the specific mailbox exists. Treat these as uncertain, not safe.
Does verification guarantee delivery?+
No. It removes the bounce risk, but inbox placement still depends on authentication, domain warmup, content, and recipient engagement.
How often should I re-verify?+
Continuously, because addresses decay as people leave jobs and abandon inboxes. Trackyr re-verifies on an ongoing basis rather than at a single point in time.
Put it into practice.
Verified creator + B2B contacts, one shared pool, paid only for what you use.
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