Format
Record Type: TXT, Hostname: _dmarc, Value(s): v, p, rua (required)

Example:

TXT    _dmarc    v=DMARC1; p=quarantine; rua=mailto:it@redcelltechnologies.com;


Notes:
You do not have to append .domian after the _dmarc . This is done for you by the DNS provider.

Change rua email address to a customer specific address.