When configured to DKIM sign outbound messages, Messaging Gateway (SMG) DKIM signs regular email as expected but does not DKIM sign Out of Office replies or other forms of delivery status notifications (DSNs).
Release : 1.0
Component : DKIM
SMG makes the decision on whether to DKIM sign messages on a per domain basis. Since deliver status notifications and out of office replies are sent using the SMTP special sender "<>", SMG has to look at the From: message header to determine whether to sign the message. If the From: header does not contain a domain configured for DKIM signing in Protocols > Domains, the message is not DKIM signed.
This is a known issue and is under investigation.
Ensure that Out of Office replies contain a From header with an email address at the domain configured for DKIM signing i.e. "From: [email protected]".