What is DKIM?
DKIM adds a digital signature to every email you send. Receivers check it against a public key in your DNS, which proves the email came from your domain and was not changed.
Email Tools
DKIM Checker
Find and validate DKIM keys, with or without the selector.
How it works
1
Enter your domain
Add your selector if you know it, or leave it empty.
2
We find the key
We look up selector._domainkey for your selector, or 30 common ones.
3
Check the key
See the key type and length, and whether it is revoked or too short.
How to find your DKIM selector
Open an email you sent in Gmail, choose Show original, and find the DKIM-Signature header. The s= value is your selector and d= is the signing domain. Or send one email to the Email Spam Test, which shows both for you.
Common DKIM selectors
- Google Workspace: google
- Microsoft 365: selector1 and selector2
- Mailchimp: k1, k2, k3
- SendGrid: s1 and s2
- Zoho Mail: zmail or a custom name
DKIM Checker features
- Looks up DKIM keys by selector, or tries 30 common selectors automatically.
- Shows the key type and an estimate of its length (1024 or 2048 bits).
- Flags revoked keys and keys shorter than 1024 bits.
- Copy the full DKIM record.
DKIM Checker FAQ
Why does the check say no DKIM key found?
Either DKIM is not turned on in your email provider, or your provider uses a selector name we did not try. Enter the selector from the s= value of an email you sent.
Is a 1024-bit key OK?
It works, but 2048-bit keys are recommended. Most providers let you create a new 2048-bit key in their settings.
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