dmarc policy blocking emails

I set up a strict dmarc policy on my domain today and I'm getting this error when sending an email from my gmail account

550 5.7.26 Unauthenticated email from<REDACTED>  is not accepted due to domain's DMARC policy. Please contact the administrator of <REDACTED> domain if this was a legitimate mail. To learn about the DMARC initiative, go to https://support.google.com/mail/?p=DmarcRejection 2adb3069b0e04-54ad6468e78sor799118e87.1 - gsmtp

How can I allow gmail to send emails on my behalf?