DKIM (DomainKeys Identified Mail) adds a digital signature to your emails that proves they came from you and weren't tampered with in transit. This article explains what a DKIM record is, how to find yours in SendX, and how to add it to your DNS correctly.
When you'll need this
Read this article if you're authenticating a domain in SendX for the first time, your DKIM verification is failing and you need to troubleshoot, you want to understand what the DKIM record does before adding it, or you're helping someone else (like IT) add your DKIM record.
What DKIM does
When you send an email through SendX, we sign it with a private cryptographic key. The matching public key is published in your DNS as a DKIM record. When an inbox provider receives your email, it:
Looks up the DKIM record in your DNS
Uses the public key to verify the signature on your email
Confirms the email is authentic and unmodified
Without DKIM, inbox providers can't verify that your email actually came from you. This makes your emails more likely to land in spam or be rejected entirely.
What the SendX DKIM record looks like
SendX uses a specific format for DKIM records:
Host/Name: sp-dkim._domainkey.yourdomain.com
Type: TXT
Value: v=DKIM1;k=rsa;s=email;h=sha256;p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQC...
The exact value depends on your domain. SendX generates a unique DKIM key for each domain you authenticate.
Finding your DKIM record in SendX
After adding your domain in SendX, you'll see four DNS records displayed. The DKIM record is the first one listed.
Click the copy icon next to the sp-dkim._domainkey record to copy it to your clipboard.
The record includes two parts you'll need:
Record Name: sp-dkim._domainkey (this goes in the Host or Name field)
Value: The full key starting with
v=DKIM1;k=rsa;s=email;h=sha256;p=...
Adding the DKIM record to your DNS
The exact steps depend on your DNS provider. Here's the general process:
Step 1: Log in to your DNS provider
Go to your domain registrar or DNS host (GoDaddy, Cloudflare, Namecheap, etc.) and log in.
Step 2: Find DNS management
Look for "DNS Settings," "DNS Management," "DNS Records," or similar. This is usually under domain settings.
Step 3: Add a new TXT record
Click "Add Record" or "Create Record" and select TXT as the record type.
Step 4: Enter the record details
Host/Name field:
Enter the host value from SendX. Depending on your provider, you may need to enter:
Just
sp-dkim._domainkey(most providers automatically append your domain)sp-dkim._domainkey.yourdomain.com(some providers require the full domain)sp-dkim._domainkey.yourdomain.com.(with trailing dot for some providers)
Value/Content field:
Paste the full value starting with v=DKIM1;k=rsa;s=email;h=sha256;p=...
TTL (Time to Live):
Use the default, or set to 3600 (1 hour) if required.
Step 5: Save the record
Click Save, Add, or Create to save your new record.
Verifying your DKIM record
After adding the record, return to SendX and verify it's working.
Click the three-dot menu next to your domain and select "Recheck Status."
If DKIM shows as verified, you're done with this record. If not, see the troubleshooting section below.
Common DKIM mistakes
Copying the record incorrectly
DKIM records are long strings with no spaces. Extra spaces, missing characters, or line breaks will break the record. Always use the copy button in SendX rather than manually selecting the text.
Wrong record type
The SendX DKIM record must be added as a TXT record. Don't use CNAME for DKIM.
Adding the domain twice in the host field
If SendX shows sp-dkim._domainkey as the host, don't add .yourdomain.com unless your provider requires the full domain. Adding it when it's not needed results in sp-dkim._domainkey.yourdomain.com.yourdomain.com, which won't work.
Quotes around the value
Some DNS providers automatically add quotes around TXT record values. Others require you to add them manually. If your record isn't verifying, try adding or removing quotes around the value.
Not waiting for propagation
DNS changes can take up to 24 hours to propagate, though most complete within a few hours. If you just added the record, wait and try again later.
Checking your DKIM record externally
You can verify your DKIM record is publicly visible using free online tools:
MXToolbox DKIM Lookup
Enter your domain and the selector sp-dkim to check if the record is published correctly.
Google Admin Toolbox
Enter your domain to check various DNS records including DKIM.
If these tools show your record but SendX still shows "Not Verified," the record may have formatting issues. Compare what the tool shows with what SendX expects.
Troubleshooting
DKIM not verifying after 24 hours
Use an external tool (MXToolbox) to check if the record is publicly visible
Compare the published record with what SendX shows
Look for extra spaces, missing characters, or formatting issues
Verify you used TXT as the record type
Check that the host field is formatted correctly for your provider
"Record not found" error
The record either wasn't added or is using the wrong host name. Double-check:
You added the record to the correct domain
The host/name field is
sp-dkim._domainkey(not justsp-dkimordkim)You didn't accidentally add the domain twice
"Invalid DKIM signature" in email headers
This usually means the record exists but the value is incorrect. Re-copy the record from SendX and replace the existing one in your DNS.
DKIM was working but stopped
DNS records can be accidentally deleted or overwritten. Check your DNS to make sure the record still exists. Also verify your domain registration hasn't lapsed.
Common questions
Why does my DKIM record look different from examples I see online?
Every DKIM record is unique to the service and domain. The public key in your record is specific to SendX and your domain. Don't copy DKIM records from examples or other services.
Can I have multiple DKIM records?
Yes. Each email service uses a different selector, so the records don't conflict. You can have DKIM records for SendX, Google Workspace, and other services all on the same domain.
What happens if I delete my DKIM record?
Your emails will fail DKIM authentication. Depending on your DMARC policy, they may be sent to spam or rejected. Don't delete the record unless you've stopped using SendX for that domain.
Do I need to update my DKIM record periodically?
No. Once added, the DKIM record remains valid unless SendX rotates keys (which is rare and would be communicated to you). You don't need to maintain or update it.
My provider says the record is too long. What do I do?
Some DNS providers have character limits for TXT records. They may require you to split the value into multiple strings enclosed in quotes. Check your provider's documentation for handling long TXT records, or contact their support.
What's the difference between sp-dkim._domainkey and other DKIM formats?
SendX uses the sp-dkim selector for its DKIM signatures. Other services use different selectors (like google, mailchimp, sendgrid). The selector is just an identifier that tells inbox providers which public key to use when verifying the signature.