DNS & Email Trust
medium Severity
Free Check
DKIM (DomainKeys Identified Mail) Selectors
Checks for cryptographic DKIM public keys used to digitally sign outbound emails and prevent tampering in transit.
Why It Matters
DKIM provides cryptographic proof that the email was actually sent by the domain owner and was not modified in transit.
How We Check This
We test common DKIM selectors (default, google, k1, s1, mailgun) for valid v=DKIM1 public keys.
How to Fix & Implement
Copy-paste configuration blocks tailored for your web server or edge proxy.
nginx snippet
# Configure selector._domainkey.yourdomain.com TXT in DNS: k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQ...
Frequently Asked Questions
What is a DKIM selector?
A selector allows a domain to maintain multiple public keys for different email services (e.g. Google Workspace vs SendGrid).