What is email verification?
Email verification checks whether an address can receive mail before anything is sent to it — confirming the domain resolves, the mail server responds, and the mailbox exists. Verification returns a status for each address rather than a simple yes or no.
Why it matters
Sending to addresses that bounce damages the sending domain's reputation, and reputation is what decides whether messages to the good addresses arrive at all. Verification also stops a rep spending a morning on a list where a large share of the rows were never deliverable.
How email verification works
- The syntax is checked against the address format rules.
- The domain is checked for mail records, which rules out addresses at domains that accept no mail at all.
- The mail server is queried to see whether it acknowledges the specific mailbox.
- The result is compared against known patterns — disposable domains, role addresses, catch-all configurations.
- A status is returned and stored with the date the check was made.
What each verification status means
| Status | What it means | What to do |
|---|---|---|
| Valid | The mailbox exists and accepts mail | Safe to send |
| Invalid | The mailbox does not exist, or rejects mail | Suppress — do not send |
| Catch-all | The domain accepts everything, so the mailbox cannot be confirmed | Send carefully, in small volumes |
| Role | A shared address such as info@ or sales@ | Rarely one person; usually exclude from outbound |
| Unknown | The server did not answer clearly | Re-check later rather than treating it as valid |
Common mistakes
- Treating catch-all as valid. A catch-all domain accepts everything, including addresses that reach nobody.
- Verifying once and never again. A verified address goes dead the moment its owner leaves.
- Mailing role addresses in an outbound sequence, then wondering why reply rates and complaint rates both look strange.
- Verifying at import rather than before send. The check is only useful at the moment the address is used.