DMARC is a technology that is designed to reduce the amount of spam that makes it into your mailbox. It provides an email’s recipient with instructions on how to validate a sender’s email.
Unfortunately, it is a voluntary standard for both the sender and the receiver and if the sender doesn’t have DMARC setup then there is nothing for the receiver to test.
In addition, if the policy tag is set to none, then the recipient is supposed to do nothing, even if the DMARC tests fail.
Microsoft is working on adding a feature to Office 365’s Advanced Threat Protection that will automatically block sender domains that failed the DMARC test.
Currently, the antispam rule allows administrators to allow domains regardless of the domain’s reputation.
This new feature will override the allow and block all domains that fail DMARC.
THE RULE IS PLANNED TO BE ADDED AROUND THIS APRIL.
Initially, email that fails will be marked as spam and handled according to the spam rules.
This will be coupled with another feature to block malicious content regardless of custom configurations, unless manually overridden.
Here is the problem.
Even if you are not an Advanced Threat Protection (ATP) customer.
Even if you are not an Office 365 customer.
Even if you don’t use Microsoft tools.
This WILL affect you.
If the company you are sending an email TO is using Office 365 ATP and they follow the recommended default configuration, if your configuration fails, your email will go into the junk box.
Your mission, should you decide to accept it – actually whether you decide to accept or not – is to make sure that your DMARC configuration is set up correctly.
Source: Bleeping Computer