Enter a domain to see which mail servers accept its email, plus the provider behind them. Builds on the same resolver used by the MailProbe API.
No signup and no logging. Free for interactive use — a script hammering this will hit the anonymous hourly limit, which is the point of the API key.
A domain with no MX records cannot receive mail, no matter how valid the address looks. Some domains skip MX entirely and rely on a fallback A record, which is legal but fragile and rarely seen in production. Every MX entry carries a priority number: lower wins. Senders try the lowest number first and move up only when the server is unreachable, so a domain with three entries at priorities 1, 5 and 10 is really saying "this one first, those two as backup."
A single MX record is a single point of failure. Two or more, usually at different providers or regions, is the normal configuration for anything serious.
| MX pattern | Provider |
|---|---|
*.google.com / aspmx.l.google.com | Google Workspace |
*.mail.protection.outlook.com | Microsoft 365 |
mx*.qq.com / *.exmail.qq.com | Tencent Exmail |
*.mail.aliyun.com | Alibaba Mail |
*.zoho.com | Zoho Mail |
*.protonmail.ch | Proton Mail |
*.mimecast.com | Mimecast (gateway) |
A gateway in front, such as Mimecast or Proofpoint, tells you the domain filters inbound mail. That usually means a corporate tenant, not a personal inbox.
The API returns the same records, plus a deliverability verdict and a reason code, in a single call.
curl "https://mailprobe.kevin-c0319.workers.dev/v1/verify?email=postmaster@example.com"
The response carries checks.mx.records with priority and exchange for each server, checks.mx.ok as a boolean, and provider when the pattern is recognised.
An MX lookup tells you whether a domain can receive mail at all. Email verification goes further: it checks the address syntax, whether the specific mailbox exists, whether the domain is a known disposable provider, and whether you likely typed the wrong domain.
Either the domain has no mail configured, or it has expired and is parked. Both mean the address will bounce. Null MX, published as a single record with a dot as the target, is a deliberate way of saying "this domain accepts no mail."
They can, but rarely. Providers migrate in scheduled windows. If you cache MX results, keep the TTL short, an hour at most.
The page is free and stays free. The underlying API has a free tier of 1,000 calls a month with a key, and an anonymous allowance for trying it out.