When the mail server says yes to everything
A catch-all domain is one whose mail server accepts every address at it, real or not, so a verifier asking whether a mailbox exists is told yes either way. No tool can confirm an address there. Cuvy returns it anyway, labelled single-source and shown with the evidence it rests on, rather than refusing or calling a guess verified.
- Catch-all means
- Every address is accepted
- What a probe proves there
- Nothing, either way
- What Cuvy returns
- The address, with its source
- The one definitive no
- A domain with no MX record
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Verification is a conversation, and this one has a single answer
It is worth knowing exactly what a verifier asks, because it explains what every tool in this market can and cannot know about your list.
The classic way to check an address is to begin delivering a message and stop before sending one. A verifier opens a connection to the mail server the domain nominates in its DNS, names the address it is asking about, and reads the reply. A server that keeps track of its own users refuses a mailbox that does not exist, and that refusal is the whole of what verification is: one server saying no on behalf of one person.
A catch-all domain is configured never to say no. Every address at it is accepted at the door and dealt with afterwards — forwarded to one inbox, filtered later, or discarded in silence. The reply for a real colleague and the reply for a typed-wrong name are the same reply. None of that is carelessness: refusing at the door tells anybody who asks which addresses exist, so accepting everything is the safer configuration, and it is the default behaviour of a great many corporate mail tenants and of the security gateways that sit in front of them.
So an address at a catch-all domain cannot be confirmed by asking — not by us, and not by whoever charged you for calling it verified. What can still be established is everything around it: whether the domain takes mail at all, whether anybody has ever been seen using that exact address, and whether it matches the shape the rest of the company uses.
One answer does survive intact. A domain with no mail server listed in its DNS accepts mail from nobody, however plausible the address looks, and that can be established from anywhere without touching a mail server at all. It is the reason a run occasionally returns nothing for a company whose website looks perfectly healthy.
Refuse to answer, or guess and call it a fact
Both responses to an unverifiable domain are in wide use, and both cost the buyer something they are not told about.
The first response is to return nothing. If it cannot be verified, it does not exist. This produces a tidy-looking file and a hole in your coverage, and the hole is not distributed at random — it falls on exactly the companies large enough to run a mail gateway, which tend to be the ones worth writing to.
The second is to guess and dress the guess. The house style of the domain is known and the person's name is known, so the address is constructed, given a confidence score and handed over. The score is arithmetic about the domain rather than evidence about the person, and once it has been written into a column headed verified, nobody downstream can tell it apart from an address a mailbox actually answered for.
Cuvy works out the house style the same way — there is no third method anybody has — and then says so in as many words. The address arrives with the line that produced it, marked single-source, and the decision about whether to send to it belongs to the person whose sending domain is at stake.
- 1
- independent source behind almost everything the corpus can find
- 5
- sightings before a pattern counts as a house style
- 90%
- of the addresses seen at that domain have to fit it
Which makes refusing to hand over single-source addresses the same thing as refusing to be useful. The share is on the billing page, with the argument it belongs to.
Two people spelled first.last at one company is a coincidence, not a policy.
Leaving room for the founder who kept a two-letter mailbox from before there was a policy.
Confirmed, single-source, and what separates them
A label here is a claim about evidence. It is not a price tier and not a prediction about whether somebody will reply.
| Row | Confirmed | Single-source |
|---|---|---|
| What happened | Two independent sources had the same address, or a verifier reached the mailbox | One sighting, or the house style filled in at a domain that accepts anything |
| What the row shows you | Which of the two it was, and which verifier answered | The single source, in the words we hold it in |
| What it does not mean | That the person will read it, or still works there | That the address is wrong — most of them are right |
| How it exports | In the sendable file | In its own file, so it cannot reach a sequence by accident |
| What it costs | 1 credit | 1 credit |
| What can change it later | A reported bounce takes it out of circulation for everybody | A second independent sighting promotes it, at no further cost |
Catch-all is the common one, not the only one
Four other reasons an address at a company is hard to stand behind, and what happens in each.
Role mailboxes
info@, sales@, careers@. Deliverable, easy to find, and attached to a company rather than a person. Shown, never counted as a find, never charged for.
Companies with no domain
The small firm whose contact address is a free mailbox. There is no house style to learn there, and a personal mailbox is not a work address, so the honest answer is a miss.
The employer that was acquired
Old mail may forward for a year or stop the week the deal closed, and the new parent spells addresses its own way. Both domains can be in play, and the person still costs one credit.
Names written backwards
Directories list people surname first. Read as written, a whole domain learns its style the wrong way round — and at a catch-all domain a reversed guess is accepted exactly like a right one.
Four steps for an address nobody can confirm
None of them involve waiting for a better verifier. There is not going to be one.
- Evidence, not a score
Read the line under the address
Every address arrives with the sentence that produced it: seen once and unconfirmed, seen by two independent sources, house style with the domain accepting anything. That sentence is the whole of what is known.
- The name, not the server
Ask what is actually in doubt
At a catch-all domain the mail server is not the problem to solve — it will never answer. What is in doubt is whether the name is spelled the way the company spells it, and how strongly the domain sticks to one style.
- Separate send
Send to the doubtful ones apart from the rest
Keep the single-source file out of the sequence that carries your main volume. A smaller, slower send limits what a wrong address costs you, and a catch-all domain will never bounce to warn you.
- The only real proof
Tell us what came back
A reply or a bounce is stronger evidence than any probe, because it is the mailbox itself answering. Report one and the address is marked against every future lookup, so it stops being handed to the next person who asks.
What people ask about unverifiable addresses
How can I tell whether a domain is catch-all?
The test anyone can run is to try an address that cannot possibly exist — a random string at the domain. A server that accepts it will accept everything. Cuvy works it out from the mail host the domain nominates and from the verifier verdict, records it against the domain, and says so in the source line on the row rather than making you check.
Does a catch-all domain mean the address will bounce?
Usually the opposite, and that is the trap. Almost nothing bounces at a catch-all domain: a wrong address is accepted and then discarded, filtered away, or left in a pile nobody reads. Your bounce rate stays low and the replies do not arrive, which is the hardest version of this to debug. A clean bounce report is not evidence that a list was right.
Why does another tool call the same address verified?
Because verified is not a regulated word. Depending on the vendor it can mean that a verifier reached the mailbox, that a mail server accepted a probe it accepts for everybody, that the address fits the pattern of the domain, or that somebody saw it somewhere years ago. The useful question is never whether a tool says verified. It is what the tool checked.
Are addresses on Google Workspace or Microsoft 365 checkable?
Sometimes. Both answer yes to every address when the tenant has catch-all switched on, which is a common default, and the security gateways that sit in front of corporate mail do the same. Where a tenant has it off, a probe means something again — which is why the answer varies domain by domain rather than by provider.
What happens when a company domain has no mail server at all?
That is the one definitive no available. A domain with no MX record in its DNS accepts mail from nobody, whatever the address looks like, so no address there is worth handing over. The person comes back as not found, in the file with the rest of the misses, and costs nothing.
Do you ever hand over info@ as if it were a person?
No. Addresses like info@ and sales@ belong to a company rather than to a person, and they are the most findable thing at any domain, which is exactly why selling one would be selling a guess about the domain. They are shown so you can see one was considered, never counted as a find, and never charged for.
Can you find anyone at a company with no domain of its own?
Often not, and we would rather say so. A two-person firm whose contact address is a free mailbox has no house style to learn and no work domain to check, and a personal mailbox is not something we sell as a work address. Those people come back as misses, which is free, rather than as a plausible-looking construction.
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