How the check works
We read the public DNS records of the domain: its MX records (which servers accept mail), its SPF record (which servers may send mail for it) and its DMARC record (what receivers should do with mail that fails those checks). We also compare the domain with lists of disposable mail services and free mailbox providers, and check whether the part before the @ is a role name such as info or support.
We never connect to the mail server. The result is built from DNS and lists only.
Reading the result
The signal at the top summarizes whether mail to this domain is likely to arrive. Good means the domain publishes working mail routing. Risky means at least one check matched, for example a disposable provider, a shared role mailbox such as info@, or no MX record with mail falling back to the domain's own address. Undeliverable means the domain cannot receive mail at all: it publishes a null MX or has no mail host.
An SPF policy of fail (-all) or soft fail (~all) is normal for a domain that sends mail. A DMARC policy of none only asks receivers to report, while quarantine and reject ask them to act on failures.
Because the mail server is not contacted, this check cannot say whether a particular mailbox exists. A good signal means the domain is set up to receive mail, not that the person is reachable.
Limits worth knowing
A domain that has the right records can still reject mail for an address that does not exist. Use this check to filter out dead, disposable and misconfigured domains early, and confirm real mailboxes by sending a message.
The free tool checks one address or domain at a time with a strict per-visitor limit. The API runs the same check at volume.
Frequently asked questions
Does this verify that a mailbox exists?
No. We do not talk to the mail server, so we cannot know whether a given address is real. We check the domain behind it.
What is an MX record?
An MX record names a server that accepts email for a domain, with a priority number. Senders try the lowest number first. A domain without MX records usually cannot receive mail.
What do SPF and DMARC do?
SPF lists the servers allowed to send mail for a domain. DMARC tells receivers what to do when a message fails SPF or DKIM checks and where to send reports. Together they make forged mail from the domain harder to deliver.
Why does it say a domain is disposable?
The domain appears on an open list of throwaway mail services. People use these to sign up without giving a lasting address.