The mailbox is either inactive, soft-deleted, or is hosted on-premise.

Question

I have an issue using Graph API for Outlook.

When I use Graph explorer I can request this endpoint:
https://graph.microsoft.com/v1.0/me/mailboxSettings

There is no issue at all.

But when doing the same call in a Blazor Server app with MSAL I get this error:
{"error":{"code":"MailboxNotEnabledForRESTAPI","message":"The mailbox is either inactive, soft-deleted, or is hosted on-premise."}}

Here is the code:

// Program.cs

builder.Services.AddRazorComponents()
    .AddInteractiveServerComponents()
    .AddMicrosoftIdentityConsentHandler();

string[]? scopes = builder.Configuration.GetSection("GraphApi:Scopes").Get<string[]>();

builder.Services.AddMicrosoftIdentityWebAppAuthentication(builder.Configuration,
       subscribeToOpenIdConnectMiddlewareDiagnosticsEvents: true)
    .EnableTokenAcquisitionToCallDownstreamApi(scopes)
    .AddDownstreamApi("GraphApi", builder.Configuration.GetSection("GraphApi"))
    .AddInMemoryTokenCaches();

builder.Services.AddControllersWithViews()
    .AddMicrosoftIdentityUI();
builder.Services.AddAuthorization(options => { options.FallbackPolicy = options.DefaultPolicy; });

// Home.razor

private async Task UseDownStreamApi(MouseEventArgs arg)
{
    try
    {
        using HttpResponseMessage response = await DownstreamApi.CallApiForUserAsync("GraphApi");
        json = await response.Content.ReadAsStringAsync();
        response.EnsureSuccessStatusCode();
    }
    catch (Exception ex)when(ex is MsalUiRequiredException || ex is MicrosoftIdentityWebChallengeUserException)
    {
        ConsentHandler.HandleException(ex);
    }
    catch (Exception ex)
    {
        json = ex.Message + "\r\n" + json;
        StateHasChanged();
    }
}

Answer 1

How are you authenticating? If using the client credentials flow, there is no logged in user, hence you cannot user /me. Use /user/{userId}/mailboxSettings instead.

Graph explorer uses delegate permissions, /me works fine therein.

Answer 2

Hello Julien Marpault,

Thank you for reaching out to Microsoft Support!

Please check whether your account lacks MS 365 License, as shown below:

You can refer to this case:

https://learn.microsoft.com/en-us/answers/questions/761931/microsoft-graph-api-throws-the-mailbox-is-either-i

Hope this helps.

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