If you want to use DMARC, you should use an aggregation tool such as ours to process the reports. You typically start with the DMARC policy in 'none' mode, which only enables reporting. Using the reports you verify that all legitimate senders are correctly signing email with DKIM (and preferably are also SPF aligned) before you switch to a 'quarantine' or 'reject' DMARC policy.
If you want to use DMARC, you should use an aggregation tool such as ours to process the reports. You typically start with the DMARC policy in 'none' mode, which only enables reporting. Using the reports you verify that all legitimate senders are correctly signing email with DKIM (and preferably are also SPF aligned) before you switch to a 'quarantine' or 'reject' DMARC policy.
[0] https://www.mailhardener.com/kb/dmarc