Microsoft’s Android app for Outlook.com, provides users to access their Outlook emails on their Android devices, fails to provide security and encryption. Email attachments are stored into easily accessible folders on the Android. App’s ‘Pin Code’ feature doesn’t protect or encrypt email data. Email data is stored locally in an unencrypted manner, and can be accessed by any malicious apps or 3rd parties with physical access to the user’s device. Pincode feature (application lock) only locks the Graphical User Interface of the app, and does nothing to ensure the confidentiality of messages and attachments.
Source: https://thehackernews.com/2014/05/microsoft-outlook-app-for-android.html