Microsoft mailbox diagnostics
Outlook email checker
Check Outlook, Hotmail and Live addresses for valid formatting, Microsoft mail routing and mailbox signals without sending a message.
Microsoft can restrict SMTP verification. Unknown means the server did not provide a reliable mailbox answer.
—verification score
Can you verify an Outlook or Hotmail address without sending mail?
You can reliably test formatting and mail-routing configuration. Microsoft’s receiving infrastructure may also expose a useful SMTP response, but it may defer or block mailbox enumeration. EmailValidly treats those cases as unknown rather than claiming the mailbox exists or does not exist.
Which Microsoft addresses are supported?
This page accepts common consumer Microsoft domains including outlook.com, hotmail.com and live.com. Microsoft 365 business addresses on custom company domains are supported by the main email checker and can often be identified from their MX records.