If you see this error, one of the "rua" or "ruf" email addresses in your report does not have a DNS TXT record verifying that they wish to receive DMARC reports for your domain.
If you want to send your DMARC reports to a domain other than the one that the record is for, then the recieving domain needs to configure a DNS record so that Email Serivce Providers know that the recipient is authorizing the the reports.
https://mxtoolbox.com/problem/dmarc/dmarc-external-validation
If your domain is domain.com and you want to send your reports to mxtoolbox.dmarc-report.com, then the recipient domain (in this case MxToolbox) needs to have a TXT DNS record
domain.com._report._dmarc.mxtoolbox.dmarc-report.com
which has the content
v=DMARC1
. Note: This record is something that the recipient of your DMARC reports needs to configure.
In the majority of cases the recipient domain will create a wild card record, which essentially means the domain is willing to receive DMARC reports for ANY domain. A wildcard record would look like this:
*._report._dmarc.example.com
with a value of "
v=DMARC1"