← Glossary
Authentication
What is DKIM selector?
A name that tells the receiver which DKIM public key to look up for a given signature.
How it works in practice
A domain can publish many DKIM keys at once, one per selector, such as google or s1. The selector appears as s= in the DKIM-Signature header and forms the DNS name selector._domainkey.yourdomain.com. Separate selectors let you run several sending services and rotate keys without downtime.
The common mistake
Looking for the key at the wrong selector and concluding that DKIM isn't set up.
Check it yourself
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