Skip to main content

Using the Office365/Exchange 2016 REST API to access Mailbox data using PowerShell part 3

In Part 1 of this continuing series I looked at the basics of accessing a Mailbox using the new REST api in PowerShell with Exchange and in Part 2 accessing all the mailboxes in a tenant as an Administrative application using Certificate authentication. In this installment I've expanded the REST PowerShell module to encompass most of the common data operations like enumerating Folder and Items.

Getting a folder from Path

A common thing you might want to do with a script that accesses a Mailbox is access a non default folder eg say a folder that a user or application has created in the Inbox. To access a folder with the REST api you need to first know the Id of that particular folder. With the WellKnownFolders in a Mailbox you can use the constants such as Inbox,SentItems etc but for non default folders you need some code that will first find the Id of the Folder by searching for the folder in question in each of the parent folders. I've added a function in the Rest module called Get-FolderFromPath which will take the Path of the folder you want to access and break down and search for each of the folder in the Path and then return the target Folder eg


Enumerating the Folders in a Mailbox

If you want to enumerate all the Folders in a Mailbox in EWS you could do a deep traversal with the  FindFolders operation which would return all the folder paged in lot of 1000. With the REST API you need to traverse each of the ChildFolders separately to return all the folders. With Exchange in EWS there where 4 different strongly typed Folder objects Mail, Tasks, Contacts and Calendar, with EWS all of these where returned with the FindFolder operation. However with the REST API only Mail Folders are returned. With the Calendar, Contacts and Tasks folder you need to use the endpoints for those folder types which also have different permissions associated. This is done so you can have apps that can access all the calendar or contact folders in a Mailbox without the need to have permissions to traverse the Mail folders (and via verse).So if your migrating an existing script its going to requires a slightly different approach from what you may have traditionally done in other API's when doing this type of enumeration.

For enumerating all the Folders in a Mailbox I have created the Get-AllMailFolders function which also appends in the FolderPath as a value add eg


Enumerating Items in a Folder

Once you have retrieved a folder the next logical thing most people want to do is enumerate the Items in that Folder. To do this I've created a few different functions in the module the most common of those is the Get-FolderItems function. This function will either take the JSON Folder object or the path of the folder you want to access and then return each of the Items so you can use it like the following


this function handles paging of the folder Items in 1000 Item pages with involves using the @odata.nextLink return value and $Top and $Skip tokens from the response.

Enumerating All Items in a Mailbox

One of the things the REST API exposes easily that EWS didn't is the ability to enumerate all Items in a Mailbox using the AllItems WellKnowFolder name. I've created a function that exposes that endpoint for the AllItems folder eg

 Get-AllMailboxItems -MailboxName gscales@datarumble.com -AccessToken $tk

Enumerating Focussed Inbox Items

The replacement to Clutter in Office365 as a way of addressing Inbox overload in Exchange is the Focused Inbox which takes advantage of the rapid development of machine learning. From a programmatic point of view the focused Inbox is exposed as a Property InferenceClassification on a Message. So to show just focused Inbox items you can use the Filter token to query for those items that are just equal to focused eg

"Inbox/messages/?`$select=ReceivedDateTime,Sender,Subject,IsRead,InferenceClassification`&`$Top=1000`&`$filter=InferenceClassification eq 'Focused'"

I've created a function called Get-FocusedInboxItems for this which you can use like the following


Get the Mailbox GUID

One last thing that comes in handy sometimes when trying to correlate data is the mailbox GUID for different users. This is now more easily available in the REST api then it was in EWS using the users endpoint. I've put together a simple function to use this called Get-MailboxUser and it can be used like


The updated REST module can be found on GitHub here https://github.com/gscales/Powershell-Scripts/blob/master/RestHttpClientMod.ps1

Popular posts from this blog

Testing and Sending email via SMTP using Opportunistic TLS and oAuth in Office365 with PowerShell

As well as EWS and Remote PowerShell (RPS) other mail protocols POP3, IMAP and SMTP have had OAuth authentication enabled in Exchange Online (Official announcement here ). A while ago I created  this script that used Opportunistic TLS to perform a Telnet style test against a SMTP server using SMTP AUTH. Now that oAuth authentication has been enabled in office365 I've updated this script to be able to use oAuth instead of SMTP Auth to test against Office365. I've also included a function to actually send a Message. Token Acquisition  To Send a Mail using oAuth you first need to get an Access token from Azure AD there are plenty of ways of doing this in PowerShell. You could use a library like MSAL or ADAL (just google your favoured method) or use a library less approach which I've included with this script . Whatever way you do this you need to make sure that your application registration  https://docs.microsoft.com/en-us/azure/active-directory/develop/quickstart-register-

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 I wrote th

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 Graph is limited to a m
All sample scripts and source code is provided by for illustrative purposes only. All examples are untested in different environments and therefore, I cannot guarantee or imply reliability, serviceability, or function of these programs.

All code contained herein is provided to you "AS IS" without any warranties of any kind. The implied warranties of non-infringement, merchantability and fitness for a particular purpose are expressly disclaimed.