How to use Invalid Email Address
- Enter an email address or domain into Invalid Email Address.
- Press the button and Invalid Email Address sends the DNS lookups from your browser.
- Read the response Invalid Email Address shows below — it comes from a public DNS resolver, not from this site.
About this tool
Invalid Email Address runs as a page in your browser. Invalid Email Address validates an address syntax locally, then checks the domain MX, SPF and DMARC records over DNS-over-HTTPS.
Proving a specific mailbox exists requires sending mail, which a browser cannot do, so Invalid Email Address focuses on the DNS signals that genuinely can be checked. The MX, SPF and DMARC checks are DNS queries sent from your browser to a public resolver; this site has no backend and never sees them, and a connection is required.
Frequently asked questions
How do I use Invalid Email Address?
Invalid Email Address validates the address format and checks the domain's MX, SPF and DMARC records via DNS from your browser.
Does Invalid Email Address cost anything?
No — Invalid Email Address is completely free, with no sign-up and no hidden limits.
Where does Invalid Email Address run its checks?
Invalid Email Address runs DNS lookups (MX, SPF, DMARC) from your browser against a public DNS-over-HTTPS resolver. This site has no backend and never sees them; the public resolver does.
Can Invalid Email Address confirm a mailbox really exists?
Invalid Email Address checks address syntax and the domain's MX, SPF and DMARC via DNS-over-HTTPS; proving a live mailbox needs to send mail, which a browser cannot do.