---
description: How API deployment works in Email Security.
title: API deployment
image: https://developers.cloudflare.com/og-docs.png
---

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# API deployment

Last updated Aug 24, 2026|Copy as Markdown|[View as Markdown](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/cloudflare-one/email-security/setup/post-delivery-deployment/api/index.md)|[Agent setup](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/agent-setup/)

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](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/cloudflare-one/email-security/settings/auto-moves/) based on your organization's policies.

![With API deployment, messages travel through Email security's email filter after reaching your users.](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/cdn-cgi/image/onerror=redirect,width=585,height=492,format=webp/_astro/M365_API_Deployment_Graph.Czbz8tQF.png) 

## 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.

## Limitations

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.

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