I am trying to use Microsoft Graph API to post a message to teams channel using SDK, I have registered an APP in Microsoft Azure, for Delegated permission, added ChannelMessage.Send and for Application permission added Teamwork.Migrate.All as per the MS documentaion – https://learn.microsoft.com/en-us/graph/api/chatmessage-post?view=graph-rest-1.0&tabs=http

I am able to fetch the token of the App (From get_access_token()) and while sending a message to one of the teams channel (get_access_token) getting failed response with below message:

{'error': {'code': 'Unauthorized', 'message': 'Message POST is allowed in application-only context only for import purposes. Refer to Import External Platform Messages - Teams  for more details.', 'innerError': {'date': '2024-09-10T14:04:38', 'request-id': '1e8cd9e8-abcd-4f92-a3e8-xxxxxxxxx', 'client-request-id': '1e8cd9e8-abcd-4f92-a3e8-xxxxxxxxx'}}}

Below is the code to fetch the token by passing the registered app client id & secrets

def get_access_token():
    url =f"https://login.microsoftonline.com/{tenant_id}/oauth2/v2.0/token"
    payload = {
        "grant_type": "client_credentials", #"client_credentials",
        "client_id": client_id,
        "client_secret": client_secret,
        "scope": "https://graph.microsoft.com/.default"
    }
    response = requests.post(url, data=payload)
    response_data = response.json()
    print(response_data)
    access_token = response_data['access_token']
    #print(access_token)
    return access_token

Below is the code to send the message with my teams & channel IDs

def send_message():
    endpoint_url = f"https://graph.microsoft.com/v1.0/teams/{team_id}/channels/{channel_id}/messages"
    access_token = get_access_token()
    headers = {
        'Authorization': f'Bearer {access_token}',
        'Content-Type': 'application/json'
    }
    request_body= {
        "body": {
            "content": "Hello world"
        }
    }
    response = requests.post(endpoint_url, headers=headers, data=json.dumps(request_body))
    print(response.status_code)
    print(response.json())

Response after executing this code

401
{'error': {'code': 'Unauthorized', 'message': 'Message POST is allowed in application-only context only for import purposes. Refer to https://docs.microsoft.com/microsoftteams/platform/graph-api/import-messages/import-external-messages-to-teams for more details.', 'innerError': {'date': '2024-09-12T13:57:54', 'request-id': '60bd5cfb-xxxx-4bea-ba58-xxxxxxxxx', 'client-request-id': '60bd5cfb-xxxx-4bea-ba58-xxxxxxxx'}}}

Seeking help to achieve this use case