How to Use PowerShell to Send Message Notifications to Windows Users

Given the constant need for systems administrators to send notifications to users — whether it’s about scheduled maintenance, policy updates, or potential security threats — it’s no wonder that the following PowerShell script is a popular one. It offers the functionality of sending toast notifications (small pop-up messages) to the currently signed-in user on a Windows computer, so admins can quickly and easily get their attention.

The Script

#Requires -Version 5.1

<#
.SYNOPSIS
    Sends a toast message/notification to the currently signed in user.
.DESCRIPTION
    Sends a toast message/notification to the currently signed in user.
    This defaults to using NinjaOne's logo in the Toast Message, but you can specify any png formatted image from a url.
    You can also specify the "ApplicationId" to any string. The default is "NinjaOne RMM".

    Setup Required: Before sending a toast message, this script needs to be ran with just the Setup parameter to prepare the computer.
     This requires running a the SYSTEM user.

    After Setup: Then the Subject and Message parameters can be used to run the script as the currently signed in user.

.EXAMPLE
     -Setup
    Sets up the registry with the default settings needed to send toast messages.
    Defaults:
        ApplicationId = "NinjaOne RMM"
        ImagePath = "C:UsersPublicPowerShellToastImage.png"
        ImageURL = "http://www.google.com/s2/favicons?sz=128&domain=www.ninjaone.com"
.EXAMPLE
     -Subject "My Subject Here" -Message "My Message Here"
    Sends the subject "My Subject Here" and message "My Message Here" as a Toast message/notification to the currently signed in user.
.EXAMPLE
     -Setup -ApplicationId "MyCompany" -ImageURL "http://www.google.com/s2/favicons?sz=128&domain=www.ninjaone.com" -ImagePath "C:UsersPublicPowerShellToastImage.png"
    Sets up the registry with the custom setting needed to send toast messages. The example below this is what you will need to use to send the toast message.
.EXAMPLE
     -Subject "My Subject Here" -Message "My Message Here" -ApplicationId "MyCompany"
    Sends the subject "My Subject Here" and message "My Message Here" as a Toast message/notification to the currently signed in user.
        ApplicationId: Creates a registry entry for your toasts called "MyCompany".
        ImageURL: Downloads a png image for the icon in the toast message/notification.
        ImagePath: Where the image will be downloaded to that all users will have access to the image.
.OUTPUTS
    None
.NOTES
    If you want to change the defaults then with in the param block.
    ImagePath uses C:UsersPublic as that is accessible by all users.
    If you want to customize the application name to show your company name,
        then look for $ApplicationId and change the content between the double quotes.

    Minimum OS Architecture Supported: Windows 10
    Release Notes:
    Initial Release
By using this script, you indicate your acceptance of the following legal terms as well as our Terms of Use at https://www.ninjaone.com/terms-of-use.
    Ownership Rights: NinjaOne owns and will continue to own all right, title, and interest in and to the script (including the copyright). NinjaOne is giving you a limited license to use the script in accordance with these legal terms. 
    Use Limitation: You may only use the script for your legitimate personal or internal business purposes, and you may not share the script with another party. 
    Republication Prohibition: Under no circumstances are you permitted to re-publish the script in any script library or website belonging to or under the control of any other software provider. 
    Warranty Disclaimer: The script is provided “as is” and “as available”, without warranty of any kind. NinjaOne makes no promise or guarantee that the script will be free from defects or that it will meet your specific needs or expectations. 
    Assumption of Risk: Your use of the script is at your own risk. You acknowledge that there are certain inherent risks in using the script, and you understand and assume each of those risks. 
    Waiver and Release: You will not hold NinjaOne responsible for any adverse or unintended consequences resulting from your use of the script, and you waive any legal or equitable rights or remedies you may have against NinjaOne relating to your use of the script. 
    EULA: If you are a NinjaOne customer, your use of the script is subject to the End User License Agreement applicable to you (EULA).
#>

[CmdletBinding(DefaultParameterSetName = "Default")]
param
(
    [Parameter(Mandatory = $true, ParameterSetName = "Default")]
    [string]
    $Subject,
    [Parameter(Mandatory = $true, ParameterSetName = "Default")]
    [string]
    $Message,
    [Parameter(ParameterSetName = "Setup")]
    [switch]
    $Setup,
    [Parameter(ParameterSetName = "Setup")]
    [string]
    $ImageURL = "http://www.google.com/s2/favicons?sz=128&domain=www.ninjaone.com",
    [Parameter(ParameterSetName = "Setup")]
    [ValidateScript({ Test-Path -Path $_ -IsValid })]
    [string]
    $ImagePath = "C:UsersPublicPowerShellToastImage.png",
    [Parameter(ParameterSetName = "Setup")]
    [Parameter(ParameterSetName = "Default")]
    [string]
    $ApplicationId = "NinjaOne RMM"
)

begin {
    function Set-ItemProp {
        param (
            $Path,
            $Name,
            $Value,
            [ValidateSet("DWord", "QWord", "String", "ExpandedString", "Binary", "MultiString", "Unknown")]
            $PropertyType = "DWord"
        )
        # Do not output errors and continue
        $ErrorActionPreference = [System.Management.Automation.ActionPreference]::SilentlyContinue
        if (-not $(Test-Path -Path $Path)) {
            # Check if path does not exist and create the path
            New-Item -Path $Path -Force | Out-Null
        }
        if ((Get-ItemProperty -Path $Path -Name $Name)) {
            # Update property and print out what it was changed from and changed to
            $CurrentValue = Get-ItemProperty -Path $Path -Name $Name
            try {
                Set-ItemProperty -Path $Path -Name $Name -Value $Value -Force -Confirm:$false -ErrorAction Stop | Out-Null
            }
            catch {
                Write-Error $_
            }
            Write-Host "$Path$Name changed from $($CurrentValue.$Name) to $((Get-ItemProperty -Path $Path -Name $Name).$Name)"
        }
        else {
            # Create property with value
            try {
                New-ItemProperty -Path $Path -Name $Name -Value $Value -PropertyType $PropertyType -Force -Confirm:$false -ErrorAction Stop | Out-Null
            }
            catch {
                Write-Error $_
            }
            Write-Host "Set $Path$Name to $((Get-ItemProperty -Path $Path -Name $Name).$Name)"
        }
        $ErrorActionPreference = [System.Management.Automation.ActionPreference]::Continue
    }
    function Test-IsElevated {
        $id = [System.Security.Principal.WindowsIdentity]::GetCurrent()
        $p = New-Object System.Security.Principal.WindowsPrincipal($id)
        $p.IsInRole([System.Security.Principal.WindowsBuiltInRole]::Administrator)
    }
    if ($Setup -and ([System.Security.Principal.WindowsIdentity]::GetCurrent().IsSystem -or $(Test-IsElevated))) {
        Set-ItemProp -Path "HKLM:SOFTWAREClassesAppUserModelId$($ApplicationId -replace 's+','.')" -Name "DisplayName" -Value $ApplicationId -PropertyType String
        Invoke-WebRequest -Uri $ImageURL -UseBasicParsing -OutFile $ImagePath
        Set-ItemProp -Path "HKLM:SOFTWAREClassesAppUserModelId$($ApplicationId -replace 's+','.')" -Name "IconUri" -Value "$ImagePath" -PropertyType String
    }
    function Show-Notification {
        [CmdletBinding()]
        Param (
            [string]
            $ToastTitle,
            [string]
            [parameter(ValueFromPipeline)]
            $ToastText
        )

        # Import all the needed libraries
        [Windows.UI.Notifications.ToastNotificationManager, Windows.UI.Notifications, ContentType = WindowsRuntime] > $null
        [Windows.UI.Notifications.ToastNotification, Windows.UI.Notifications, ContentType = WindowsRuntime] > $null
        [Windows.System.User, Windows.System, ContentType = WindowsRuntime] > $null
        [Windows.System.UserType, Windows.System, ContentType = WindowsRuntime] > $null
        [Windows.System.UserAuthenticationStatus, Windows.System, ContentType = WindowsRuntime] > $null

        # Make sure that we can use the toast manager, also checks if the service is running and responding
        try {
            $ToastNotifier = [Windows.UI.Notifications.ToastNotificationManager]::CreateToastNotifier($ApplicationId)
        }
        catch {
            Write-Error $_
            Write-Host "Failed to create notification."
        }

        # Use a template for our toast message
        $Template = [Windows.UI.Notifications.ToastNotificationManager]::GetTemplateContent([Windows.UI.Notifications.ToastTemplateType]::ToastImageAndText02)
        $RawXml = [xml] $Template.GetXml()

        # Edit the template to our liking, in this case just the Title, Message, and path to an image file
        $($RawXml.toast.visual.binding.text | Where-Object { $_.id -eq "1" }).AppendChild($RawXml.CreateTextNode($ToastTitle)) > $null
        $($RawXml.toast.visual.binding.text | Where-Object { $_.id -eq "2" }).AppendChild($RawXml.CreateTextNode($ToastText)) > $null
        if ($NodeImg = $RawXml.SelectSingleNode('//image[@id = ''1'']')) {
            $NodeImg.SetAttribute('src', $ImagePath) > $null
        }

        # Serialized Xml for later consumption
        $SerializedXml = New-Object Windows.Data.Xml.Dom.XmlDocument
        $SerializedXml.LoadXml($RawXml.OuterXml)

        # Setup how are toast will act, such as expiration time
        $Toast = $null
        $Toast = [Windows.UI.Notifications.ToastNotification]::new($SerializedXml)
        $Toast.Tag = "PowerShell"
        $Toast.Group = "PowerShell"
        $Toast.ExpirationTime = [DateTimeOffset]::Now.AddMinutes(1)

        # Show our message to the user
        $ToastNotifier.Show($Toast)
    }
}
process {
    # Make sure that Setup was used and that we are running with elevated privileges
    if ($Setup -and ([System.Security.Principal.WindowsIdentity]::GetCurrent().IsSystem -or $(Test-IsElevated))) {
        Write-Host "Used $ImageURL for the default image and saved to $ImagePath"
        Write-Host "ApplicationID: $ApplicationId"
        Write-Host "System is ready to send Toast Messages to the currently logged on user."
        exit 0
    }
    elseif ($Setup -and -not ([System.Security.Principal.WindowsIdentity]::GetCurrent().IsSystem -or $(Test-IsElevated))) {
        Write-Error "Failed to setup registry."
        Write-Host "Please run script as SYSTEM or as a user with administrator privileges."
        exit 1
    }

    try {
        if ($(Get-ItemPropertyValue -Path "HKLM:SOFTWAREClassesAppUserModelId$($ApplicationId -replace 's+','.')" -Name "DisplayName" -ErrorAction SilentlyContinue) -like $ApplicationId) {
            Show-Notification -ToastTitle $Subject -ToastText $Message -ErrorAction Stop
        }
        else {
            Write-Error "ApplicationId($ApplicationId) was not found in the registry."
            Write-Host "Please run script as an administrator or as the SYSTEM account with the -Setup parameter."
        }
    }
    catch {
        Write-Error $_
        exit 1
    }
    exit 0
}
end {}

 

Detailed Breakdown

The script initiates by defining parameters for the notification message: Subject, Message, Setup, ImageURL, ImagePath, and ApplicationId. Post-definition, the script checks whether it’s being run with elevated rights (as an admin).

For the initial setup:

• It creates or updates a registry entry to identify the application sending the toast.
• Downloads a specified image (by default, from NinjaOne) which will appear on the toast message.
• Updates the image path in the registry.

Subsequently, whenever the script is run to send a notification, it checks for the registry entry and then utilizes Windows’ built-in toast notification system to display the message.

Potential Use Cases

Let’s say you’re an IT professional serving a large corporation. A crucial software update is about to be pushed, and there’s a need to inform all employees about potential downtime. Instead of relying on emails — which often go unread — the admin can utilize this PowerShell script to send a direct notification to each user’s computer, ensuring visibility and timely information dissemination.

Comparisons

While there are alternative methods to send messages, like using the “msg” command or “Net Send,” this script’s advantage lies in its modern approach. Traditional methods send plain text messages, whereas this PowerShell script allows for richer content like images and custom application IDs. Furthermore, the script ties well with platforms like NinjaOne, thus making it more cohesive for RMM tasks.

FAQs

• Can I customize the image on the toast message? 
  Yes, you can specify any png image URL for customization.
• Do I need to run the setup every time? 
  No, setup only needs to be run once, preferably with administrative rights. Subsequent uses can just send the message.
• Is there any OS limitation? 
  The script is designed for Windows 10 and later.

Implications

While the script simplifies notifications, it’s crucial to note that any scripts altering the registry must be executed with care. Inaccurate modifications can have unintended system consequences. Moreover, for IT security, ensuring that the script source is trustworthy is vital to avoid potential backdoors or vulnerabilities.

Recommendations

• Always backup the registry before making changes.
• Use the script in a test environment first.
• Avoid overloading users with too many toast messages to prevent “notification fatigue.”

Final Thoughts

In the age of instant communication, tools like this PowerShell script embody the efficiency IT departments strive for. NinjaOne’s integration potential with such scripts highlights the platform’s versatility, ensuring IT professionals stay one step ahead in system management and user communication. With such tools in their arsenal, IT departments can ensure that important alerts never go unnoticed.