Trend Micro Email Security verifies DKIM signatures in incoming email messages and allows administrators to take actions on messages that fail to pass signature verification. If a message's DKIM signature passes verification, the message will continue to the next step in the regular delivery process.
The DKIM verification settings apply only to the selected recipient domain.
The Add DKIM Verification Settings screen appears.
X-Header is added to indicate whether DKIM verification is successful or not.
Here are some examples of X-Header:
X-TM-Authentication-Results:dkim=pass; No signatures and verification is not enforced
X-TM-Authentication-Results:dkim=pass; No valid signatures and verification is not enforced
X-TM-Authentication-Results:dkim=fail; No processed signatures but verification is enforced
X-TM-Authentication-Results:dkim=pass; Contain verified signature, header.d=test.com, header.s=TM-DKIM_201603291435, firstname.lastname@example.org
X-TM-Authentication-Results:dkim=fail; No verified signatures
Do not intercept messages
Delete entire message
Tags can be customized. When selecting the Tag subject action, note the following:
This action may destroy the existing DKIM signatures in email messages, leading to a DKIM verification failure by the downstream mail server.
To prevent tags from breaking digital signatures, select Do not tag digitally signed messages.
Each email message from the specified domain must meet specific criteria of the DKIM standard; otherwise, an action will be taken on the message.
The following criteria must be met:
The sender domain must have a DKIM record.
There is at least one verified signature in the message.