Enter a domain or an email address. We try common DKIM selectors automatically; if you know yours (the s= value in a message's DKIM-Signature header), add it. Nothing is sent and nothing is stored.
How email deliverability works
Every email you send passes a quick ID check before it reaches an inbox. This one-minute animation shows the three checks this tool looks at, and what happens when someone tries to fake your address.
The three checks at a glance
SPF
The guest list
DKIM
The tamper-proof seal
DMARC