DMARC - What is it?
DMARC, which stands for "Domain-based Message Authentication, Reporting & Conformance", is a technical specification created by a group of organizations that want to help reduce the potential for email-based abuse by solving a couple of long-standing operational, deployment, and reporting issues related to email authentication protocols.
DMARC standardizes how email receivers perform email authentication using the well-known SPF and DKIM mechanisms. This means that senders will experience consistent authentication results for their messages at AOL, Gmail, Hotmail, Yahoo! and any other email receiver implementing DMARC. We hope this will encourage senders to more broadly authenticate their outbound email which can make email a more reliable way to communicate.
Why is DMARC Important?
With the rise of the social internet and the ubiquity of e-commerce, spammers and phishers have a tremendous financial incentive to compromise user accounts, enabling theft of passwords, bank accounts, credit cards, and more. Email is easy to spoof and criminals have found spoofing to be a proven way to exploit user trust of well-known brands. Simply inserting the logo of a well known brand into an email gives it instant legitimacy with many users.
Users can't tell a real message from a fake one, and large mailbox providers have to make very difficult (and frequently incorrect) choices about which messages to deliver and which ones might harm users. Senders remain largely unaware of problems with their authentication practices because there's no scalable way for them to indicate they want feedback and where it should be sent. Those attempting new SPF and DKIM deployment proceed very slowly and cautiously because the lack of feedback also means they have no good way to monitor progress and debug problems.
DMARC addresses these issues, helping email senders and receivers work together to better secure emails, protecting users and brands from painfully costly abuse.
How Does DMARC Work?
A DMARC policy allows a sender to indicate that their emails are protected by SPF and/or DKIM, and tells a receiver what to do if neither of those authentication methods passes - such as junk or reject the message. DMARC removes guesswork from the receiver's handling of these failed messages, limiting or eliminating the user's exposure to potentially fraudulent & harmful messages. DMARC also provides a way for the email receiver to report back to the sender about messages that pass and/or fail DMARC evaluation.
Who Can Use DMARC?
DMARC policies are published in the public Domain Name System (DNS), and available to everyone. Because the specification is available with no licensing or similar restriction, any interested party is free to implement it.
Source: Please login or register to see this link.