This is part 2 in my REST series in which we will look at AppOnly tokens. These are the Tokens you would look to use when you want to write an application or script that would access every mailbox in an Office365 Tenant. For an Admin or DevOps person looking at what they might want to do with the new REST API this is useful when your looking to write something that will tweak a config setting on all Mailboxes to comply with a certain Organization policy (no matter how insane) or do some custom Item task that isn't supported in any of the Admin cmdlets. To simplify AppOnly tokens as much as I can they are an Oauth Access token that are requested using Certificate Authentication. Then depending on what Application permission scopes have been allowed for the app in Azure eg your script or app will be able to access that particular Mailbox data across all the Mailboxes within your tenant. In EWS if you understood how impersonation worked this is a kind of an equivalent but a lo
Pushing the Envelope in Messaging and Office 365 Development