Mailbox Automapping forward and reverse map using Autodiscover and PowerShell

Auto-mapping was a feature that was introduced in Exchange 2010, where when you added Mailbox access permission via Add-MailboxPermission, Outlook would automatically add that Mailbox as an additional Mailbox. Outlook uses Autodiscover to get the information on these mailboxes that are auto mapped via the AlternateMailboxes user setting eg in XML it comes back like the following

One thing you can't see easily via the Exchange Managed Shell cmdlet is which ACE's (Access Control Entries) have Automapping enabled on a particular Mailboxes DACL and which don't. You also can't easily see from one mailbox which mailboxes will be auto mapped to it (basically a reverse mapping).So the purpose of this script is to provide both a forward and reverse mapping of Automapping setting for a collection of Mailboxes that are passed into to. It produces a report that look like

To get this collection you can either use a CSV file of addresses, Get-Mailbox or just a static list.

Eg to run the script using Get-Mailbox

create a blank collection
$Mailboxes = @()

populate the collection
Get-Mailbox -ResultSize Unlimited | foreach-object{$Mailboxes += $_.PrimarySMTPAddress}

then run the script like

Get-AutoDiscoverMailboxMap -Mailboxes $Mailboxes

The report is outputted in the last line of the script.

I've put a copy of this script on GitHub here https://github.com/gscales/Powershell-Scripts/blob/master/AutoDiscoverMap.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 MimeMessage via the Microsoft Graph using the Graph SDK, MimeKit and MSAL

One of the new features added to the Microsoft Graph recently was the ability to create and send Mime Messages (you have been able to get Message as Mime for a while). This is useful in a number of different scenarios especially when trying to create a Message with inline Images which has historically been hard to do with both the Graph and EWS (if you don't use MIME). It also opens up using SMIME for encryption and a more easy migration path for sending using SMTP in some apps. MimeKit is a great open source library for parsing and creating MIME messages so it offers a really easy solution for tackling this issue. The current documentation on Send message via MIME lacks any real sample so I've put together a quick console app that use MSAL, MIME kit and the Graph SDK to send a Message via MIME. As the current Graph SDK also doesn't support sending via MIME either there is a workaround for this in the future my guess is this will be supported.

Export calendar Items to a CSV file using Microsoft Graph and Powershell

For the last couple of years the most constantly popular post by number of views on this blog has been Export calendar Items to a CSV file using EWS and Powershell closely followed by the contact exports scripts. It goes to show this is just a perennial issue that exists around Mail servers, I think the first VBS script I wrote to do this type of thing was late 90's against Exchange 5.5 using cdo 1.2. Now it's 2020 and if your running Office365 you should really be using the Microsoft Graph API to do this. So what I've done is create a PowerShell Module (and I made it a one file script for those that are more comfortable with that format) that's a port of the EWS script above that is so popular. This script uses the ADAL library for Modern Authentication (which if you grab the library from the PowerShell gallery will come down with the module). Most EWS properties map one to one with the Graph and the Graph actually provides better information on recurrences then...

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