Free tool · live DNS
DKIM record checker
Find a domain's DKIM keys and check their strength. No selector at hand? We try the most common ones.
No selector? We try the common ones (Google Workspace, Microsoft 365, Mailchimp, SendGrid …). Find yours in the s= tag of the DKIM-Signature header of an email you sent.
Common DKIM selectors
| Provider | Selector(s) |
|---|---|
| Google Workspace | google |
| Microsoft 365 | selector1, selector2 |
| Mailchimp / Mandrill | k1, k2, k3, mandrill |
| SendGrid | s1, s2 |
| Zoho Mail | zmail, zoho |
| Proton Mail | protonmail, protonmail2, protonmail3 |
| Fastmail | fm1, fm2, fm3 |
Amazon SES and many other services use random selectors; read them from a sent message.
A DKIM record
google._domainkey.example.com. TXT "v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA…"
v=DKIM1– versionk=rsa– key type (rsa or ed25519)p=– the public key; empty means the key was revokedt=y– test mode
Frequently asked questions
What is DKIM?
DomainKeys Identified Mail adds a cryptographic signature to every email. The receiver fetches the public key from DNS (selector._domainkey.yourdomain.com) and verifies that the message was sent by the domain and not changed on the way.
How do I find my DKIM selector?
Open an email you sent, show the original message or headers, and find the DKIM-Signature header. The selector is the s= value, the domain is the d= value.
Which DKIM key length should I use?
2048-bit RSA. 1024-bit keys still work but are considered weak; keys below 1024 bits are rejected by major mailbox providers.
What are common DKIM selectors?
google (Google Workspace), selector1 and selector2 (Microsoft 365), k1 (Mailchimp), s1 and s2 (SendGrid), and many providers use default or dkim.
Email validation API
Validate emails in your app
emailvalidation.io checks syntax, MX records and the mailbox over SMTP, flags disposable, role and free addresses and returns a quality score, in one request.
Read the docs100 free validations every month. No credit card required.
GET https://api.emailvalidation.io/v1/info?email=name@company.com
{
"email": "support@emailvalidation.io",
"domain": "emailvalidation.io",
"format_valid": true,
"mx_found": true,
"smtp_check": true,
"disposable": false,
"role": true,
"free": false,
"score": 0.64,
"state": "deliverable",
"reason": "valid_mailbox"
}Free email tools
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