As of February 1st, Gmail and Yahoo will start enforcing a requirement for Domain-based Message Authentication, Reporting and Conformance (“DMARC“). DMARC is an IETF protocol as specified in RFC7489. It will initially affect large senders, defined as domains originating more than 5K emails per day into the Gmail system (this is the shape of things to come however, it will be increasingly more difficult to get your email delivered in the absence of SPF, DKIM and DMARC). It works with SPF and DKIM...