Last year, we announced that on November 2018, we will stop supporting Basic Authentication in the Office 365   Outlook REST API v1.0 and this is a follow up announcement to reiterate that we will be decommissioning Basic Authentication in Outlook REST API v1.0 this month. This means that new or existing apps will not be able to use Basic Authentication in v1.0 and Beta versions of Outlook REST API starting December 2018.
Over the last few years, we have been investing in services that help developers access information in Office 365 in a simple and intuitive way. As we make progress in this journey, some technologies become obsolete, because they no longer provide the best way to interact with Office 365 data. When this occurs, we follow our service deprecation policy and announce these services as being deprecated.
Next steps
If you have been using Basic Authentication in Office 365 Outlook REST API v1.0/Beta in your app, you should immediately transition to Microsoft Graph-based Outlook REST APIs to continue accessing Exchange Online data. For more information and details on how to make the transition, please refer to the following articles:
Getting started with Microsoft Graph using OAuth2
Transitioning from Outlook v1.0 to Microsoft Graph
Thank you in advance for updating and opening your apps to a wider range of useful and intelligent features on Microsoft Graph. We are extremely excited about the growing opportunities that Microsoft Graph offers to developers. And, we remain fully committed to continue our journey to empower developers to build innovative applications on Office 365.
Happy coding!
Microsoft Graph Team