office 365 Mail flow in Hybrid Deployment

1. Scenario 1 – MX record points to Office 365, and Office 365 filters all messages
2. Scenario 2 - MX record points to Office 365, and mail is filtered on-premises
3. Scenario 3 – MX record points to your on-premises servers
4.  Scenario 4 – MX record points to your on-premises server, Your on-premises server relay messages to the internet through Office 365.