How to check if an email address exists
You can check three things without sending anything: that the address is correctly formed, that its domain has a mail server, and, if the server answers honestly, that the mailbox exists. Some servers do not answer honestly, so a clear yes is not always possible.
ValidReach Team · Updated 2026-10-26
1. Format
One @, a plausible domain and allowed characters. This catches typos like ana@northwind,example.test.
2. Domain
Look up the domain’s MX records. A domain with no mail server cannot receive mail. The free MX lookup shows them.
3. Mailbox
A verifier opens a connection to the mail server and asks whether it would accept the recipient, then ends without sending a message. A server that accepts any recipient is a catch-all, and one that delays the first contact (greylisting) may return unknown.
Good to know
Do not test by sending a message and watching for a bounce on a list you care about: the bounce counts against your reputation. Catch-all domains cannot be confirmed either way.