How do I check a domain's DKIM record if I don't know the selector?

Leave the DKIM Selector field blank and enter your domain name. KaijuVerifier automatically scans the 14 most common DKIM selectors (google, selector1, selector2, k1, s1, default, mail, dkim, mandrill, zendesk1, protonmail) in parallel and displays every active public key.

Why does RSA key length (1024-bit vs 2048-bit) matter for DKIM?

1024-bit RSA keys are considered cryptographically weak and are flagged by modern spam filters. Google Workspace, Microsoft 365, and RFC 8301 recommend at least 2048-bit RSA keys (or Ed25519) for DKIM signing.

What does an empty p= tag mean in a DKIM TXT record?

An empty p= tag (v=DKIM1; p=) explicitly tells receiving mail servers that the DKIM public key for that selector has been revoked.

📜 SPF Checker 🔑 DKIM Checker 🔒 DMARC Checker ⚙️ DKIM Key Generator

AUTO-DISCOVERS 14 COMMON SELECTORS · RSA 1024/2048-BIT KEY AUDITOR

Free DKIM Record Checker & Selector Lookup

Inspect any domain's selector._domainkey TXT record, verify v=DKIM1 syntax, measure the exact RSA public key bit-length (1024-bit vs 2048-bit), or leave the selector blank to auto-scan 14 popular ESP selectors.

⚡ Quick Test (Auto-Scan Selectors):

Common DKIM Selectors by Email Provider (2026 Cheat Sheet)

Unlike SPF and DMARC, DKIM records live under a specific selector subdomain (<selector>._domainkey.yourdomain.com) so a domain can use multiple sending services simultaneously. Here are the default selectors used by major providers:

Email Provider / ESP	Default DKIM Selector(s)	DNS Hostname Format
Google Workspace	`google`	`google._domainkey.domain.com`
Microsoft 365 / Exchange	`selector1`, `selector2`	`selector1._domainkey.domain.com`
Mailchimp / Mandrill	`k1`, `k2`, `k3`, `mandrill`	`k2._domainkey.domain.com`
SendGrid	`s1`, `s2`	`s1._domainkey.domain.com`
ProtonMail	`protonmail`, `protonmail2`, `protonmail3`	`protonmail._domainkey.domain.com`
cPanel / Postfix / Custom	`default`, `mail`, `dkim`	`default._domainkey.domain.com`

Need to generate a new 2048-bit RSA DKIM keypair for your own mail server? Use our Free DKIM Key & Record Generator, or pair your DKIM setup with our SPF Record Generator and DMARC Record Generator.