Email verification: what an answer means

Email verification evaluates whether available evidence supports a mailbox outcome at the time of checking. The result can be valid, invalid, or unknown. Refresh List reports the provider outcome and available reasons without turning an inconclusive check into a delivery promise, a permission signal, or an invented confidence score.

Last updated 2026-09-14. Read the scope and limitations before applying a result.

Key points

Valid is not a delivery guarantee.
Unknown is distinct from invalid.
Each completed unique check uses one credit.

Detailed explanation

Mailbox evidence and sending performance answer different questions. Addresses change; receiving systems can reject particular senders. Read the outcome alongside its reason and checking context.

Example

A valid result today does not establish that the inbox will exist next month.

How Refresh List handles it

the configured verification service supplies mailbox outcomes. Preflight is separate. Valid, invalid, and unknown checks are charged equally.

Limitations

No independent Refresh List accuracy benchmark is claimed. Additional signals require supporting evidence.

Methodology and sources

Product behavior is described from the current Refresh List implementation and provider contract. Protocol context should be checked against the applicable standards and provider documentation. This page does not create a benchmark or certification.