Yet another acronym, DMARC (Domain-based Message Authentication, Reporting & Conformance). This became very important due to the high-profile phishing done by russian state sponsored hacking groups involving spoofed e-mail addresses. By sending e-mails that looked as coming from credible sources they were able to infect systems connected to political entities: Clinton campaign staff, democrat party convention etc.
  So first a link explaining what is DMARC: DMARC.ORG, then a nice explanation with diagrams  SPF, DKIM and DMARC brief explanation and best practices 
  A tutorial on how to implement it in an organization Step-By-Step Instructions to Implement DMARC in Your Organization
  A more technical tutorial Installing OpenDMARC RPM via Yum with Postfix or Sendmail (for RHEL / CentOS / Fedora)
  An online tool to check if your domain has DMARC DMARC Domain Status Checker
  Maybe the high-profile phishing actions that made the news will make the adoption of e-mail authentication faster.
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