Start with the address itself
Format checks can identify malformed input. That is useful, but a correctly formatted address is only the beginning. An address can have the right shape while pointing to a nonexistent domain or an unavailable mailbox.
Look at the domain
Mail-related DNS information helps establish how a domain handles email. Temporary DNS failures need to be distinguished from a stable configuration problem. An unexplained “bad” label hides that difference.
Understand the mailbox response
Receiving systems do not all reveal the same information. A provider may return a clear response, restrict verification, or accept recipients in a way that does not confirm an individual mailbox. The result should explain what was actually learned.
Read risk flags in context
Disposable and role-based flags describe characteristics of an address. Catch-all describes relevant domain behavior. None should be interpreted without considering the underlying reason and your use case.
Keep separate questions separate
Verification is not permission to send. It is not proof of ownership. It is not an inbox-placement test. Use it alongside the controls that answer those other questions.
A practical next step
Read one result with its reason and timestamp before designing a rule for thousands of rows. See the MailCheckup results guide for the categories used by the product.
A real-world example
A correctly formatted address can belong to a domain with working mail infrastructure while the individual mailbox remains uncertain. That is why one successful check should not erase the result of another. Keep the chain of evidence visible.
What to take back to your team
Define which categories are accepted, reviewed, or suppressed. Keep ownership confirmation and permission records outside the verification result so that each decision remains explainable.
Review one representative record with your team. Agree on the evidence, the decision, and who owns the next step before applying the same rule to a complete list.