How to access and restore deleted Items (Recoverable Items) in the Exchange Online Mailbox dumpster with the Microsoft Graph API and PowerShell

As the information on how to do this would cover multiple posts, I've bound this into a series of mini post docs in my GitHub Repo to try and make this subject a little easier to understand and hopefully navigate for most people.

The Binder index is https://gscales.github.io/Graph-Powershell-101-Binder/

The topics covered are

How you can access the Recoverable Items Folders (and get the size of these folders)

How you can access and search for items in the Deletions and Purges Folders and also how you can Export an item to an Eml from that folder

How you can Restore a Deleted Item back to the folder it was deleted from (using the Last Active Parent FolderId)

and the sample script is located

https://github.com/gscales/Powershell-Scripts/blob/master/Graph101/Dumpster.ps1

The MailboxConcurrency limit and using Batching in the Microsoft Graph API

If your getting an error such as Application is over its MailboxConcurrency limit while using the Microsoft Graph API this post may help you understand why. Background The Mailbox concurrency limit when your using the Graph API is 4 as per https://docs.microsoft.com/en-us/graph/throttling#outlook-service-limits . This is evaluated for each app ID and mailbox combination so this means you can have different apps running under the same credentials and the poor behavior of one won't cause the other to be throttled. If you compared that to EWS you could have up to 27 concurrent connections but they are shared across all apps on a first come first served basis. Batching Batching in the Graph API is a way of combining multiple requests into a single HTTP request. Batching in the Exchange Mail API's EWS and MAPI has been around for a long time and its common, for email Apps to process large numbers of smaller items for a variety of reasons. Batching in the Gr...

Sending a Message in Exchange Online via REST from an Arduino MKR1000

This is part 2 of my MKR1000 article, in this previous post I looked at sending a Message via EWS using Basic Authentication. In this Post I'll look at using the new Outlook REST API which requires using OAuth authentication to get an Access Token. The prerequisites for this sketch are the same as in the other post with the addition of the ArduinoJson library https://github.com/bblanchon/ArduinoJson which is used to parse the Authentication Results to extract the Access Token. Also the SSL certificates for the login.windows.net and outlook.office365.com need to be uploaded to the devices using the wifi101 Firmware updater. To use Token Authentication you need to register an Application in Azure https://msdn.microsoft.com/en-us/office/office365/howto/add-common-consent-manually with the Mail.Send permission. The application should be a Native Client app that use the Out of Band Callback urn:ietf:wg:oauth:2.0:oob. You ...

How to test SMTP using Opportunistic TLS with Powershell and grab the public certificate a SMTP server is using

Most email services these day employ Opportunistic TLS when trying to send Messages which means that wherever possible the Messages will be encrypted rather then the plain text legacy of SMTP. This method was defined in RFC 3207 "SMTP Service Extension for Secure SMTP over Transport Layer Security" and there's a quite a good explanation of Opportunistic TLS on Wikipedia https://en.wikipedia.org/wiki/Opportunistic_TLS . This is used for both Server to Server (eg MTA to MTA) and Client to server (Eg a Message client like Outlook which acts as a MSA) the later being generally Authenticated. Basically it allows you to have a normal plain text SMTP conversation that is then upgraded to TLS using the STARTTLS verb. Not all servers will support this verb so if its not supported then a message is just sent as Plain text. TLS relies on PKI certificates and the administrative issue s that come around certificate management like expired certificates which is why ...

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