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Not only that you might not trust Microsoft to securely store and safeguard your data including your credentials, but also, providing your user credentials to a third party is a breach of many IT usage policies. The Outlook app doesn’t even make clear to end users that this is occurring. In fact, the typical end user would have no idea that this is happening.
2 - Outlook App weakens MFA protection Outlook app does not always provide a unique device ID
. If a user runs the Outlook App on multiple devices of the same OS, then Outlook App will provide the same device ID for the user on those devices. This will weaken the enforcement of MFA that is based on the device ID.
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