Office365-SendMail_GraphAPI

# Define AppId, secret and scope, your tenant name and endpoint URL
$ClientID = ''
$ClientSecret = ''
$tenantDomain = "domain.onmicrosoft.com"

$emailSender = "shared@domain.com"
$emailRecipient = $emailSender
$emailSubject = "Email sent via GraphAPI"

$emailBody = "<h1>Incoming Email</h1>`n"
$emailBody += "<p>Date: $(Get-Date)</p>`n"
$emailBody += "Email sent by GraphAPI"


$loginURL = "https://login.microsoft.com"
$resource = "https://graph.microsoft.com"
$body       = @{grant_type="client_credentials";resource=$resource;client_id=$ClientID;client_secret=$ClientSecret}
$oauth      = Invoke-RestMethod -Method Post -Uri $loginURL/$tenantdomain/oauth2/token?api-version=1.0 -Body $body


if ($null -ne $oauth.access_token) {
    
    $reqBody='{
        "message": {
        "subject": "",
        "body": {
            "contentType": "",
            "content": ""
        },
        "toRecipients": [
            {
            "emailAddress": {
                "address": ""
            }
            }
        ]
        }
    }' | ConvertFrom-Json

    $reqBody.message.subject = $emailSubject
    $reqBody.message.body.contentType = "Html"
    $reqBody.message.toRecipients.emailAddress.address = $emailRecipient
    $reqBody.message.body.content = $emailBody
    
    Invoke-RestMethod -Method Post -Uri "https://graph.microsoft.com/v1.0/users/$($emailSender)/sendMail" -Headers @{'Authorization'="$($oauth.token_type) $($oauth.access_token)"; 'Content-type'="application/json"} -Body ($reqBody | ConvertTo-Json -Depth 4 | Out-String)
     
}