Purpose
This test checks for the following:

• If the campaign passes DomainKeys Identified Mail (DKIM) authentication
• Whether the DKIM key length provides proper security protection

How it works
When a campaign is sent to Inbox Monitor:

• Inbox Optimizer checks the Yahoo! Authentication result header using the first Yahoo! seed received. The Yahoo! seed checked on your message can be verified by opening the DKIM fix-it guide within the Inbox Optimizer test results and clicking on the icon beside See your authentication results.
• Inbox Optimizer scans your DKIM signature, and using your selector (s=) and domain (d=),  the key length is determined by viewing the public key.

Results
DKIM authentication:

• Pass: If the Yahoo! authentication header shows a passed test
• Fail: If the Yahoo! authentication header shows a failed test

DKIM key length:

• Pass: If the DKIM key length is at least 1024 bits
• Warn: If the DKIM key length is less than 1024 bits