Are there any downsides to using DMARC?

DMARC is a valuable tool that can help protect your email from being spoofed, but it does have some limitations. One such factor is that DMARC only applies to email messages sent from your domain. If someone else sends an email message on your behalf, DMARC will not protect it. Besides, DMARC does not work with email messages sent through third-party services, such as Gmail or Yahoo! Mail.