In Garoon version 5.5.1 or later, you can use Google or Microsoft advanced authentication (OAuth 2.0) for sending and receiving e-mails.
This page explains how to configure OAuth authentication for Google and Microsoft.
You cannot use OAuth authentication if you are not using HTTPS for running Garoon.

This page explains the steps to set up a service provided by a third party (a service provider), and the steps may be changed at any time by the service provider's own discretion.
Cybozu cannot guarantee the completeness and/or accuracy of the setup steps provided in this page, and Cybozu is not responsible for any errors or failures that you as the customer may encounter during the setup.
Please consult with the service provider for more information.