C# console application - "The mailbox is either inactive, soft-deleted, or is hosted on-premise."

Question

I'm trying to send an email from a c# console application. I've created an azure app and have the clientId and Clientsecret

Trying to send a mail with the following code throws the ODataError with message in title. Any idea?

public static async Task SendAsync(string toAddress, string subject, string content)
{
    string? tenantName = "[email protected]";
    string? tenantId = "xx";
    string? clientId = "xx";

    string? clientSecret = "xx";
    //string[] scopes = new string[] { "user.read", "Mail.Send" };
    string[] scopes = new string[] { "https://graph.microsoft.com/.default" };

    ClientSecretCredential credential = new(tenantId, 
        clientId,
        clientSecret, 
        new TokenCredentialOptions { AuthorityHost = AzureAuthorityHosts.AzurePublicCloud });

    var graphServiceClient = new GraphServiceClient(credential, scopes);

    var requestBody = new Microsoft.Graph.Users.Item.SendMail.SendMailPostRequestBody
    {           
        Message = new()
        {
            Subject = subject,
            Body = new ItemBody
            {
                ContentType = BodyType.Html,
                Content = content
            },
            ToRecipients = new List<Recipient>()
            {
                new Recipient
                {
                    EmailAddress = new EmailAddress
                    {
                        Address = toAddress
                    }
                }
            },
        },
        SaveToSentItems = true,
    };

    try
    {
        await graphServiceClient.Users[tenantName].SendMail.PostAsync(requestBody);
    }
    catch (Microsoft.Graph.Models.ODataErrors.ODataError ex)
    {
        Console.WriteLine(ex.Message);
    }

}

I have the following permissions:

Answer 1

I agree with @DarkBee, the error usually occurs if the user does not have an active Office 365 license assigned.

Initially, I too got same error when I tried to send mail from user having no valid license:

To resolve the error, make sure to assign one active Office 365 license to the user:

When I ran below code after assigning license to the user, I got response like this:

using Azure.Identity;
using Microsoft.Graph;
using Microsoft.Graph.Models;
using Microsoft.Graph.Models.ODataErrors;

var scopes = new[] { "https://graph.microsoft.com/.default" };

var user = "[email protected]";

var clientId = "appId";
var tenantId = "tenantId";
var clientSecret = "secret";

var options = new ClientSecretCredentialOptions
{
    AuthorityHost = AzureAuthorityHosts.AzurePublicCloud,
};

var clientSecretCredential = new ClientSecretCredential(
    tenantId, clientId, clientSecret, options);

var graphClient = new GraphServiceClient(clientSecretCredential, scopes);

var requestBody = new Microsoft.Graph.Users.Item.SendMail.SendMailPostRequestBody
{
    Message = new Message
    {
        Subject = "Send mail - Demo purpose",
        Body = new ItemBody
        {
            ContentType = BodyType.Html,
            Content = "Hi! This is Sri",
        },
        ToRecipients = new List<Recipient>
        {
            new Recipient
            {
                EmailAddress = new EmailAddress
                {
                    Address = "[email protected]",
                },
            },
        },
    },
    SaveToSentItems = true,
};
try
{
    await graphClient.Users[user].SendMail.PostAsync(requestBody);
    Console.WriteLine("Successfully sent mail");
}
catch (ODataError odataError)
{
    Console.WriteLine(odataError.Error.Message);
}

Response:

To confirm that, I checked the same in user's Sent Items where mail sent successfully as below: