DMARC Best practices for O365 user:
1. Enable DMARC HONOR policy in your Microsoft Admin panel.
Action: Login to your Admin panel> Go to Security> Policies & rules> Threat Policy> Anti phishing> Anti Phishing Policy> Edit Action.
Follow below Screenshot for Policy reference and save it.
2. Your own domain should not be whitelisted in anti-spam policies.
Action: ensure the domain is not whitelisted in any Anti-Spam or other policies.
3. Typo-squatting domain(s) should be blocked in incoming email server/gateway appliance.
Action: You will be receiving typo-squatting Domain alert on mail from GoDMARC Team. You can block these domains in your incoming email security or email server.
4. Threat IPs should be blocked.
Action: Under Aggregate reports refer to SPF and DKIM both fail, download those IPs and block them in your incoming email security or email server.
5. IP reputation should be monitored for genuine sources, especially email marketing.
Action: Check the reputation of your IP on the GoDMARC Dashboard. If a poor reputation is found, connect with your Email provider as it may cause emails to land in spam folder.
6. Follow below link to secure your tenant by adding DMARC and DKIM to you .onmicrosoft.com domain.
https://godmarc.freshdesk.com/a/solutions/articles/82000911071