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Scripting Teams Urgent Messages for a Set of Users

A reader asked if it was possible to write a PowerShell script to send chats to a set of people when something important happened, like a failure in an important piece of plant or a medical emergency. They explained that they have the facility to broadcast this kind of information via email, but a lot of their internal communications have moved to Teams and they’d like to move this kind of scripted communication too.

Teams supports urgent messages for one-to-one chats. Originally, these messages were called priority notifications and Microsoft planned to charge for their use. That idea disappeared in the mists of the Covid pandemic, and anyone can send urgent messages today. The nice thing about urgent messages is that Teams pings the recipient every two minutes until they read the message or twenty minutes elapses.

  • Run the Connect-MgGraph cmdlet to connect to the Graph. Delegated permissions must be used, and I specified the Chat.ReadWrite and User.Read.All permissions.
  • Because the script works with delegated permissions, the chats are sent by the signed-in user. The script runs the Get-MgContext cmdlet to find out what that account is.
  • The script sends chats to a set of users. Any Entra ID group will do.
  • The New-MgChatMessage cmdlet eventually sends the chat message. Because I want to include an inline image and a mention in the message, work must be done to construct the payload needed to tell Teams what content to post.
  • In Graph requests, this information is transmitted in JSON format. PowerShell cmdlets don’t accept parameters in the same way. Three different parameters are involved – the body, the mention, and the hosted content (image uploaded to Teams). Each parameter is passed as a hash table or array, and if the parameter takes an array, it’s likely to include some hash tables. Internally, Teams converts these structures to JSON and submits them to the Graph request. You don’t need to care about that, but constructing the various arrays and hash tables takes some trial and error to get right. The examples included in Microsoft documentation are helpful but are static examples of JSON that are hard to work with programmatically. I use a different approach. Here’s an example of creating the hash table to hold details of the inline image:
# Create a hash table to hold the image content that's used with the HostedContents parameter
$ContentDataDetails = @{}
$ContentDataDetails.Add("@microsoft.graph.temporaryId", "1")
$ContentDataDetails.Add("contentBytes", [System.IO.File]::ReadAllBytes("$ContentFile"))
$ContentDataDetails.Add("contentType", "image/jpeg")
[array]$ContentData = $ContentDataDetails
  • After populating the hash tables and arrays, the script runs the New-MgChat cmdlet. If an existing one-on-one chat exists for the two users, Teams returns the identifier of that chat thread. If not, Teams creates a new chat thread and returns that identifier.
  • The script runs the New-MgChatMessage cmdlet to post the prepared message to the target chat thread. Setting the importance parameter to “urgent” marks this as a Teams urgent message.
$ChatMessage = New-MgChatMessage -ChatId $NewChat.Id -Body $Body -Mentions $MentionIds -HostedContents $ContentData -Importance Urgent

The Urgent Teams Message

Teams urgent message created with PowerShell.
Figure 1: Teams urgent message created with PowerShell

You can download the script from GitHub.

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Plain Sailing After Understanding Parameter Formatting

There’s no doubt that it’s more complicated to create and send one-to-one chats than it is to send email to a group of recipients, especially if you stray away from a very simple message body. However, much of the complexity is getting your head around the formatting of parameter input. Once you understand that, it’s reasonably easy to master the rest of the code.

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