DKIM Key Generator
Create an RSA key pair for DKIM and get a ready-to-use DNS TXT record.
DKIM Checker validates a domain's DKIM signature. Finds the public key in DNS (selector._domainkey.example.com), validates format, checks key size (≥ 2048-bit recommended). Shows selectors for major ESPs: Gmail, Outlook, Mailgun, SendGrid.
e.g. mail, google, dkim. Used in the DNS record name.
Private Key (PKCS#8)
Save this key on your mail server. Keep it secret.
DNS TXT Record
Add this TXT record to your domain's DNS.
TXT
Setup Guide
- Copy the private key and save it to
/etc/mail/dkim/mail.private - Add the TXT record to your domain's DNS (via your registrar's DNS panel)
- Wait for DNS propagation (usually 15–60 minutes)
- Verify the setup: send an email and check the
DKIM-Signatureheader
Why teams trust us
How it works
Enter domain and selector
Fetch DKIM TXT record
Validate public key
What is DKIM?
DKIM (DomainKeys Identified Mail) is a mechanism to digitally sign email with a key stored in DNS. This allows recipients to verify that the email was genuinely sent from the specified domain.
Selector-based Check
Specify domain and DKIM selector — get the public key and its parameters.
Key Analysis
RSA/Ed25519 key length, hash algorithm, flags, and validity period.
Recommendations
If key < 2048 bits — we issue a warning and key rotation instructions.
Instant Result
Direct DNS query in seconds — no waiting for TTL.
Who uses this
Email marketers
pre-send verification
Sysadmins
mail server setup
Security
phishing protection audit
Developers
email deliverability debug
Common Mistakes
Best Practices
Get more with a free account
DKIM check history and DNS monitoring for domain record changes.
Sign up freeWhat is DKIM and Why Does It Matter for Email Deliverability?
DKIM (DomainKeys Identified Mail) adds a cryptographic signature to outgoing emails, allowing receiving servers to verify the message was sent by an authorised domain and was not modified in transit. The signature is published as a TXT record in DNS under a selector subdomain — for example, mail._domainkey.example.com. Without DKIM, emails are more likely to be flagged as spam or rejected by major providers such as Gmail and Outlook.
Learn more
Frequently Asked Questions
What is DKIM?
DKIM (DomainKeys Identified Mail) is an email authentication method using digital signatures. Protects against email spoofing.
How to set up DKIM?
Generate keys with our tool, add a TXT record to your domain DNS. Detailed instructions on the page.
What key size to choose?
We recommend 2048 bits — optimal balance of security and compatibility. 1024 is outdated, 4096 may not fit in a TXT record.
Related guides
Longer-form reading on this topic from the knowledge base.
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