DomainKeys Identified Mail (DKIM) is an email authentication system designed to detect email spoofing. It allows organizations to take responsibility for transmitting a message, while providing a mechanism to verify that the message was not altered during transit.  DKIM uses cryptographic signatures and public-key infrastructure to verify that an email message has not been altered during transit and that it truly came from the claimed sender. Email senders can use DKIM to sign their messages by adding a DKIM-Signature header field to the messages. Email receivers can then use the public key published in the DNS to verify the signature and check that the message has not been tampered with. 

How to configure DKIM for TrendMicro HES

• Visit Outbound Protection > DomainKeys Identified Mail (DKIM) Signing.
• Click Add
• From the Domain name drop-down menu in the, select a specific sender domain.
• Add screen for DKIM signing
• Click “Enable DKIM signing.”
• Configure general DKIM signing settings these include:

Choose a signing domain identifier from the drop-down list using the SDID field.
Subdivide key namespace with a selector. keep the default setting.
Headers to sign: Choose one or more headers, and if necessary, make changes to additional headers.
Specify the amount of time that must pass before a key pair becomes active. Once Hosted Email Security locates the public key in the DNS, it begins to track the wait time.
To create a key pair, select “Generate.”

• Finally, copy the DNS record that was configured to your clipboard.

How to publish DKIM record in DNS for TrendMicro HES:

• Access your DNS administration interface.
• Make a TXT record in your DNS called ._domainkey with the following format: s1._domainkey.yourdomainname.com
• Paste the DKIM public key’s copied contents into the space designated for the TXT record value.
• Click “Save.”

Use our free DKIM record lookup tool to validate the published DKIM record.

Enable DMARC for your domains to protect against spoofing. Sign up for a free trial today!

For more information on TrendMicro DKIM setup, you can refer to their reference documentation