Fixing t_dkim_invalid (DKIM Signature Issue) in Emails

Check DKIM Signature on Your Domain

Before troubleshooting, verify your DKIM records.

For other DKIM/SPF/DMARC fixes, see "DKIM signature, not necessarily valid", DKIM Temperror, check-auth@verifier.port25.com, and Configuring Mail Records (MX, SPF, DKIM, DMARC) in ISPmanager.

Test Your DKIM Configuration

Run this command to check DKIM on your domain:

dig TXT default._domainkey.yourdomain.com +short

Replace yourdomain.com with your actual domain.

If you get a valid response, it should look like this:

"v=DKIM1; k=rsa; p=MIGf... (your public DKIM key)"

If it's missing or incorrect, proceed to Step 2.

Verify DKIM in cPanel or Your DNS Provider

Check DKIM in cPanel (If Using cPanel)

1. Log in to cPanel (https://yourdomain.com:2083).
2. Go to Email Deliverability.
3. Find your domain and check the DKIM status.
4. If DKIM is missing, click Generate DKIM Record and copy the TXT record.

If using Cloudflare, Namecheap, or GoDaddy DNS, manually add the TXT record.

Correct the DKIM DNS Record

If your DKIM record is missing or incorrect, update it manually.

Correct DKIM TXT Record Format

In your DNS provider (Cloudflare, GoDaddy, Namecheap, etc.), add the following TXT record:

• Host: default._domainkey
• Type: TXT
• Value:

v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQE... (your public DKIM key)

• TTL: 3600 (1 hour)

Save changes and wait for DNS propagation (can take 24-48 hours).

Restart Mail Services (For Mail Servers)

If your mail server is not signing emails correctly, restart the necessary services.

For Exim (cPanel Servers)

service exim restart

For Postfix

systemctl restart postfix

For OpenDKIM (If Used)

systemctl restart opendkim

Send a test email after restarting.

Verify DKIM with an Online Tool

After fixing your DKIM record, test it using:

• MXToolBox DKIM Lookup
• Mail Tester

If DKIM passes, your email authentication is fixed.

Summary of Fixes

Now your emails should pass DKIM validation and avoid spam filters!