The DMARC register (Domain-based Message Authentication, Reporting, and Conformance) is used to improve email security by specifying how an email service should handle messages that fail the SPF and DKIM authentication tests.

To set up a DMARC record for Google Workspace, your domain's DNS record might look something like this:

v=DMARC1; p=none; rua=mailto:dmarc-reports@seudominio.com; ruf=mailto:dmarc-failure-reports@seudominio.com; fo=1;

In this example:

v=DMARC1 indicates the version of the DMARC record.
p=none defines the policy for handling e-mails that fail DMARC tests. none means that no specific action is taken, but this can be changed to quarantine (send emails to quarantine) or reject (reject emails) depending on your needs.
rua=mailto:dmarc-reports@seudominio.com specifies where the aggregated DMARC reports should be sent. Replace dmarc-reports@seudominio.com with the e-mail address where you want to receive these reports.
ruf=mailto:dmarc-failure-reports@seudominio.com indicates where forensic failure reports should be sent. Replace dmarc-failure-reports@seudominio.com with the appropriate e-mail address.
fo=1 determines the conditions under which forensic failure reports are generated. 1 means that reports are generated if there are failures in SPF or DKIM.

Remember that DMARC configuration must be done carefully, as misconfigured policies can affect email delivery. It is therefore advisable to start with a policy none and monitor reports before moving on to more restrictive policies such as quarantine or reject.

It is also essential to replace the e-mail addresses in the fields street e ruf their own e-mail addresses to receive DMARC reports.