Guest access is one of the ways in Office365 of collaborating between different organizations which allows you to give certain people who are outside of your company access to a limited subset of the resources you have in the Cloud. This can be an Office365 unified Group or Microsoft Team but also other workloads like SharePoint and OneDrive can utilize this. When it comes to scripting there are a number of value add things you can do to automate tasks for different people who have guest accounts in another tenant. The first step to automating with Guest Access is to Authenticate and generate an access token in the Guest tenant. Getting the Guest Tenants Authorization Endpoint Before you can authenticate you need to first obtain the Guest tenants Authorization endpoint for the tenant where the Guest Account exists in. To do this you can make a simple Get Request like the following Invoke-WebRequest -uri ("[https://login.windows.net/{0}/.well-known/openid-configu
Pushing the Envelope in Messaging and Office 365 Development