Graph API Users's MailBox

Question

I'm working on office 365 mail's backup using Microsoft Graph SDK in windows forms application.

I want get get all users mails using office 365 administrator account.May i know what are permission i need to provide.?

I can get mails from logged in account (office 365 administrator) but not for others users.

below is the example code.

var messages = await graphClient.Users[UserID].MailFolders[MailFolderID].Messages
.Request()
.GetAsync();

Thanks,
Babu.

Answer 1

Hi Babu -

I order to get to another user's mailbox - and the other user hasn't delegated their mailbox access in Exchange Online (like an administrative assistant might do) - you need to use Application permissions rather than Delegated (which acts on behalf of the user). Here is the relevant documentation on the call: https://learn.microsoft.com/en-us/graph/api/user-list-messages?view=graph-rest-1.0&tabs=http
Notice that there are three kinds of permissions listed - you need "Application" permissions.

To get those you need to use Client Credentials Flow - see https://learn.microsoft.com/en-us/azure/active-directory/develop/v2-oauth2-client-creds-grant-flow for details.

Once you get this working - you are likely to run into throttling issues if you try to load a large volume of email. Details are here: https://learn.microsoft.com/en-us/graph/throttling

Thanks and best of luck!

Answer 2

@BobGerman-9536 - Thanks for your answer.

I'm not sure how to do this

To get those you need to use Client Credentials Flow - see https://learn.microsoft.com/en-us/azure/active-directory/develop/v2-oauth2-client-creds-grant-flow for details.

I want to do this on C# Windows Forms Application. I'm explaining below.

1. Getting Token

                try
                    {
                        authResult = await app.AcquireTokenInteractive(scopes)
                            .WithAccount(accounts.FirstOrDefault())
                            .WithPrompt(Microsoft.Identity.Client.Prompt.SelectAccount)
                            .ExecuteAsync();
                        AccessToken = authResult.AccessToken.ToString();
                    }
                    catch (MsalException msalex)
                    {
                        WriteLog("Error(GetAccessToken()) MsalException: " + msalex.Message.ToString());
                    }
   

2. using the above token i'm creating "graphClient"

try
{
graphClient = new GraphServiceClient(
"https://graph.microsoft.com/v1.0",
new DelegateAuthenticationProvider(
async (requestMessage) =>
{
var token = AccessToken;
requestMessage.Headers.Authorization = new AuthenticationHeaderValue("bearer", AccessToken);
requestMessage.Headers.Add("xxx", "yyyy");

                         }));
                 return graphClient;
             }

1. using the graphClient I'm listig the users.

                 var users = await graphClient.Users
                           .Request()
                           .GetAsync();
   

From this users list how can i access all user mailbox. (note: this is working for the account when i give to get token but not for all the users.) I gave all the application permissions but still not working.

Code: ErrorAccessDenied
Message: Access is denied. Check credentials and try again.

Thankss,
Babu.