Send Mail with Attachment, PowerShell, and Microsoft Graph API

API Reference and Permissions

The official documentation is here:

• Send mail – Microsoft Graph v1.0 | Microsoft Docs
• fileAttachment resource type – Microsoft Graph v1.0 | Microsoft Docs

Azure App Registration Rights:

• Mail.Send

The PowerShell Script to send Mail with Attachment using MS GRAPH API

That’s the Script on using PowerShell with MS GRAPH API to send a Mail with an Attachment.

#Configure Mail Properties
$MailSender = "sender@company.com"
$Attachment = "C:\Users\you\OneDrive - test_folder\Hello World.docx"
$Recipient = "recipient@company.com"

#Get File Name and Base64 string
$FileName = (Get-Item -Path $Attachment).name
$base64string = [Convert]::ToBase64String([IO.File]::ReadAllBytes($Attachment))


#Connect to GRAPH API
$tokenBody = @{
    Grant_Type    = "client_credentials"
    Scope         = "https://graph.microsoft.com/.default"
    Client_Id     = $clientId
    Client_Secret = $clientSecret
}
$tokenResponse = Invoke-RestMethod -Uri "https://login.microsoftonline.com/$tenantID/oauth2/v2.0/token" -Method POST -Body $tokenBody
$headers = @{
    "Authorization" = "Bearer $($tokenResponse.access_token)"
    "Content-type"  = "application/json"
}

#Send Mail    
$URLsend = "https://graph.microsoft.com/v1.0/users/$MailSender/sendMail"
$BodyJsonsend = @"
                    {
                        "message": {
                          "subject": "Hello World from Microsoft Graph API",
                          "body": {
                            "contentType": "HTML",
                            "content": "This Mail is sent via Microsoft <br>
                            GRAPH <br>
                            API<br>
                            and an Attachment <br>
                            "
                          },
                          
                          "toRecipients": [
                            {
                              "emailAddress": {
                                "address": "$Recipient"
                              }
                            }
                          ]
                          ,"attachments": [
                            {
                              "@odata.type": "#microsoft.graph.fileAttachment",
                              "name": "$FileName",
                              "contentType": "text/plain",
                              "contentBytes": "$base64string"
                            }
                          ]
                        },
                        "saveToSentItems": "false"
                      }
"@

Invoke-RestMethod -Method POST -Uri $URLsend -Headers $headers -Body $BodyJsonsend