Friday, June 09, 2017

Using the Office365/Exchange 2016 REST API to access Mailbox data using PowerShell part 5 Sending

Following on from my previous posts in this series, I've made a number of changes to the Exch-REST PowerShell  module to increase its functionality.

The first is that it now supports using either the Microsoft Graph endpoint or the Outlook REST endpoint which has been default so far. If you want to know which endpoint you should use have a look at https://dev.office.com/chooseapiendpoint . The advantage of utilizing the graph endpoint is that it allows you to hook into all the other Office365 services like Groups,OneDrive,SharePoint, Onenote etc using the same endpoint and token (I'll have some example in future posts).

To utilize the graph endpoint is easy all you need to do is add one additional parameter when you create the token to specify you want the AccessToken for the graph eg

$Token = Get-AccessToken -MailboxName mailbox@domain.com `
                         -ClientId 5471030d-f311-4c5d-91ef-74ca885463a7 `
                         -redirectUrl urn:ietf:wg:oauth:2.0:oob         
                         -ResourceURL graph.microsoft.com    
All the other cmdlets will then look at the AccessToken`s resource property using the new Get-Endpoint function and return the appropriate endpoint. If you want to use the preview endpoints you would need to tweak this function to return the appropriate preview endpoint.

function Get-EndPoint{
        param(
        [Parameter(Position=0, Mandatory=$true)] [psObject]$AccessToken,
        [Parameter(Position=1, Mandatory=$true)] [psObject]$Segment
    )
    Begin{
        $EndPoint = "https://outlook.office.com/api/v2.0"
        switch($AccessToken.resource){
            "https://outlook.office.com" {  $EndPoint = "https://outlook.office.com/api/v2.0/" + $Segment }     
            "https://graph.microsoft.com" {  $EndPoint = "https://graph.microsoft.com/v1.0/" + $Segment  }     
        }
        return , $EndPoint
        
    }
}
The only quirk I've come across with the difference between the two endpoints is when using extended properties the Name used to identify the Property is PropertyId in the REST endpoint and Id in Graph Endpoint (when making GET). The module has partial coverage for this but its an area that needs some work and will improve with future updates.

I've also added one more AccessToken creation function that allows you to pass in the username and password via a PSCredential. This requires that you have implicit authentication enabled in your app configuration manifest see oauth2AllowImplicitFlow

I've also added functions for Item Creation, Sending messages and Attachment enumeration and downloading and it now stores the Tokens in securestrings.

Also thanks to Elijah Gagne there is also some proper getting started documentation in the GitHub Repo  https://github.com/gscales/Exch-Rest/blob/master/README.md

I've added some samples for using the Send-MessageREST function which is what you would use when you want to send a Message. This function covers all the Send Message bases it can send a Message normally as a user, Send a Message On Behalf or SendAS, and also it can handle allowing you to set the ReplyTo header to allow a different reply to address as well as set Delivery and Read Recipients. The samples page can be found https://github.com/gscales/Exch-Rest/blob/master/Samples/SendMessageExamples.md .

A full example that gets an Access token to send a Message with an Attachment would look like

$Mailbox = "user@domain.com"
$Subject = "Test Message"
$Body = "Test Body of Message"
$To = @(New-EmailAddress -Address user@domain.com)

$Attachment = @("c:\temp\attachmentfile.doc")



$AccessToken = Get-AccessToken -MailboxName $Mailbox -ClientId 5471030d-f311-4c5d-91ef-74ca885463a7 -redirectUrl urn:ietf:wg:oauth:2.0:oob
Send-MessageREST -MailboxName $Mailbox  -AccessToken $AccessToken -ToRecipients $To -Subject $Subject -Body $Body -Attachments $Attachment   
The module is available from the PowerShell Gallery https://www.powershellgallery.com/packages/Exch-Rest and the source from Github
https://github.com/gscales/Exch-Rest


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