DMARC is an open email authentication method that builds on existing standards SPF and DKIM and enables domain-level protection of the email channel. It’s the first technology that can prevent spoofing of the header from: domain (what users see in their email client). DMARC defines how the receiver should handle messages depending on the results of SPF and DKIM checks. If SPF and DKIM are enabled, DMARC will handle messages as follows:
Decision Matrix of DMARC Policies
The DMARC decision matrix shows how DMARC handles messages in case of passed or failed DKIM and SPF checks.
DMARC Decision Matrix
|SPF and DKIM Check||DMARC Result||Result|
|SPF pass + DKIM pass||DMARC pass||Deliver|
|SPF pass + DKIM fail||DMARC fail||Quarantine|
|SPF fail + DKIM pass||DMARC fail||Quarantine|
|SPF fail + DKIM fail||DMARC fail||Quarantine|
The table shows that only if both the SPF and DKIM checks have been passed, the DMARC result is
positive and the email will be delivered. Otherwise, the email will be quarantined.
Enabling DMARC Checking for inbound mail
To use DMARC first complete these steps for the desired domain:
• Activate SPF Type 2 checking
• Activate DKIM
• Create a DMARC policy record (TXT resource record) in DNS to announce what an email receiver should do with non-aligned mail it receives. Here is an example of a basic DMARC policy record to start with:
v=DMARC1; p=none; fo=1; rua=mailto:email@example.com; ruf=mailto:firstname.lastname@example.org
Then send an email with the subject 'Enable DMARC' to email@example.com and include the following details:
• For which domains you want to activate DMARC Checking
• Request or confirm that SPF Type 2 checking and DKIM are activated for these domains
• Confirm that a DMARC policy record has been added for each domain
EveryCloud doesn’t provide any DMARC reporting services at this time.
Logging of inbound email filtered by DMARC
Emails detected by DMARC and found not to comply with the SPF and/or DKIM policies will be quarantined and displayed in the spam report and control panel.
These emails are displayed in the control panel with ase-dmarc as the reason.