For those who want IBM Domino to support DMARC in a future version, please create a PMR to attach to SPR #LCAY9PEEH4 / APAR LO82157.
What is DMARC?
DMARC is a mechanism to have the server to add a cryptographic signature to outbound e-mails / to verify this signature in inbound emails to ensure the email is really coming from the sender it pretends to come from.
More details here http://www.dmarc.org/