DKIM Validator guide hub
DKIM Validator guides
Practical guides for DKIM Validator: examples, troubleshooting steps, and links to the matching DN01 tool.
DKIM Selector Explained: How selector._domainkey Works
What a DKIM selector is, where it appears in DNS, and why mail providers use different selectors for signing keys.
How to Find Your DKIM Selector
Practical places to find DKIM selectors in Google Workspace, Microsoft 365, Amazon SES, Mailchimp, SendGrid and email headers.
DKIM p= Tag: Public Key Checks That Matter
How to read the DKIM p= public key tag, why empty p= revokes a key, and what truncated DNS TXT records look like.
DKIM 1024 vs 2048 Bit Keys: What to Use
Why 2048-bit DKIM keys are preferred, when 1024-bit keys still appear, and how key length affects DNS TXT records.
DKIM t=y Testing Mode: When to Remove It
What the DKIM t=y flag means, why it is useful during rollout, and why it should not stay forever.
How to Rotate DKIM Keys Safely
A safe workflow for publishing a new selector, switching signing, waiting out TTL, and retiring the old DKIM key.
Google Workspace DKIM Check: Selector and TXT Record
How Google Workspace DKIM records are named, what the google selector means, and how to troubleshoot missing or invalid records.
Microsoft 365 DKIM: selector1 and selector2 Explained
Why Microsoft 365 uses selector1 and selector2, how CNAME-based DKIM publishing works, and what to check when validation fails.