DMARC: Invalid policy syntax
What this means
A ‘_dmarc’ record has been found, however the record has an invalid syntax.
Why this is a problem
If a DMARC record has an invalid syntax, it will not be processed and therefore not enforced.
This increases the chances of spoofed emails being sent from your domain, and in some circumstances it can affect email deliverability.
How to check if the problem is there
Check your DMARC record for any unusual characters or contents. A DMARC record should contain the following tags at a minimum:
v=DMARC1; p=<action>;
<action> can be the following states
none
quarantine
reject
All tags must be separated by a semicolon ‘;’. A space is not mandatory but is recommended for readability.
You might want to use the following online tools to check for this issue:
- National Cyber Security Centre’s (NCSC) check your email security tool
- Hardenize’s domain report tool
How to fix this
Amend your DMARC record so that it contains a valid syntax.
Pay particular attention to incorrect symbols or mistyped tags which may have been introduced by text editors.
Also pay attention to the email address format on any reporting tags as these must conform to a particular syntax.
Check the following NCSC guidance on how to configure a DMARC policy: