Improve email deliverability with the Mailmodo DKIM checker
Many emails fail authentication on recipient servers because DKIM (DomainKeys Identified Mail) records are missing or incorrect. This results in lower deliverability and a greater risk of landing in spam folders.
Mailmodo addresses this with its free DKIM Record Checker, which confirms your domain’s DNS has the DKIM record published in the correct location. A properly configured DKIM record signals to receiving mail servers that your messages genuinely come from your domain, thereby lowering the risk of your messages being filtered out.
How to use the Mailmodo DKIM record checker tool?
Step 1: In your email client, choose a message sent from your domain that you'd like to verify.
Step 2: Look for options like "View original", "Show source", or "View headers". These show the raw message headers.
Step 3: Find the DKIM-Signature header. You can do this in two ways:
Manually, by scanning the headers for the line that starts with DKIM-Signature.
Use the Find Selector tab in the tool to extract the selector and domain for you automatically.
Step 4: In the DKIM-Signature header, look for the s= and d= fields.
For example: DKIM-Signature: ... s=mail123; d=yourdomain.com;
- Step 5: In the DKIM + Selector tab, enter the selector (s=) and the domain (d=). The tool will check your DNS and show whether the DKIM record is correctly published and valid.
4 Common DKIM issues and how to fix them
Issue 1: No DKIM record found
This is one of the most common messages you’ll see from DKIM checkers. It means the tool couldn’t find a DKIM TXT record for the domain and selector you entered.
To troubleshoot this, start by confirming that the selector and domain you entered are accurate. If the record seems correct but still isn't showing, log in to your DNS provider and check that it exists under selector._domainkey.yourdomain.com. If it was added recently, it might just need more time to propagate.
Issue 2: Missing or invalid public key (p=)
When a DKIM checker shows the p= tag as missing or empty, it usually means the public key wasn’t saved correctly in your DNS or got cut off during publishing.
For this, go back to the DNS panel and review the DKIM TXT record to make sure the key is complete. Some providers may ask the key to be split into multiple parts or wrapped in quotes.
Issue 3: Syntax errors in the DKIM record
Your DKIM record should start with v=DKIM1; and include tags like k=rsa; and a valid p= key, each separated by semicolons. Small typos or accidental line breaks can cause the record to fail verification.
To fix this, carefully review the record for any formatting mistakes. If you copied the key from another source, make sure it wasn’t altered during the process.
Issue 4: Multiple DKIM records for the same selector
Having more than one DKIM TXT record published under the same selector can confuse mail servers and can cause your emails to fail verification or be rejected because servers aren’t sure which key to trust.
It’s important to review your DNS records and remove any duplicate entries for that selector. Only one valid DKIM record should exist per selector. If you’ve recently changed providers or keys, make sure to delete old or unused records.
You can learn more about DKIM and about setting it up in this detailed guide- What Is DomainKeys Identified Mail (DKIM) & How Does It Work ?
