A quarter of a business list comes back as a shrug
The results are back and a large block of them says catch-all. On a business list that's routinely around 28%, and it is the single most common reason people go looking for a different verifier.
A different verifier won't resolve it. Some vendors return a guess instead of the label. That improves their accuracy figure and makes your list worse, because the guesses land in your valid pile.
The order the work happens in
Understand what the server actually said
Probing a random nonexistent address at the domain also returned success. That means the server accepts everything, so no reply distinguishes a real mailbox from an invented one.
Sort the catch-alls by what you know
A catch-all address that opened a campaign last month is a person. One from a purchased file is a guess. The verdict is identical and the risk is nothing alike.
Match the decision to the send
Include them in a warm campaign to engaged contacts. Exclude them from a first send on a new account, from a re-engagement campaign and from any cold sequence.
Send them separately when you do send
In their own batch, so their bounce rate is visible on its own rather than averaged into a campaign you were relying on.
Let engagement be the evidence
Two campaigns with no bounce and an open is stronger evidence than any protocol probe could give you. That's the only resolution mechanism that exists here.
What each result means here
The same four results and their flags, read against this job. A catch-all worth keeping in one situation is one to exclude in another.
| Result | What to do with it |
|---|---|
| Valid | Not available on these domains. That is the point of the label. |
| Invalid | Also unavailable. A catch-all server will not reject anything, including addresses that do not exist. |
| Catch-all | Keep, tag, and decide by the send. Never merge into valid, and never delete for being unresolvable. |
| Unknown | A different thing: the server refused to answer rather than accepting everything. Re-checking can change an unknown and cannot change a catch-all. |
| Role flag | Both flags on one address is common at larger companies and adds nothing to the decision. |
| Disposable flag | Some throwaway providers run catch-all domains. Remove on the disposable flag. |
How you know it is finished
Catch-all results sit in their own segment with a tag, they are excluded from every send where the reputation risk is real, and nothing in your pipeline has quietly reclassified them as valid.
What this does not fix
Catch-all results are a verdict we return rather than a non-answer, so they are billed as a check. Unknowns are the ones never billed, and the difference between those two labels is worth understanding before comparing any two vendors on price.
Questions people ask
Can catch-all email addresses be verified?
Not at mailbox level, by anyone. The domain is configured to accept every recipient, so a probe for a real address and a probe for an invented one get the same reply. A vendor returning a verdict here is inferring, not verifying.
Should I delete catch-all addresses?
No. They're disproportionately your business contacts and many of them are real. Tag them, keep them out of your risky sends, and let engagement sort them out.
Why does one verifier call these valid?
Because guessing raises an accuracy figure that is calculated on the addresses it judged. The unresolvable ones are where the difficulty lives, and resolving them by assumption makes the number look better and the list worse.
Try it on the file in front of you
100 free checks a month, no card. Addresses we could not get an answer on come back labeled as unknown, and those are not billed.