API deployment

When you choose an API deployment, email messages only reach Email Security after they have already reached a user’s inbox.

Then, through an integration with your email provider, Email Security can auto-move messages based on your organization’s policies.

With API deployment, messages travel through Email Security's email filter after reaching your users.

Benefits

When you choose API deployment, you get the following benefits:

Easy protection for complex email architectures, without requiring any change to mailflow operations.
Agentless deployment for Microsoft 365.
The initial email protection measures offered by your current email provider.

However, API deployment also has the following disadvantages:

Email Security is dependent on Microsoft’s Graph API, and outages will increase the message dwell time in the inbox.
Your email provider may throttle API requests from Email Security.
Email Security requires read and write access to mailboxes.
Requires API support from your email provider (does not typically support on-premise providers).
Detection rates may be lower if multiple solutions exist.
Messages cannot be modified or quarantined.