Код:
Код: Выделить всё
var scopes = new[] { "https://graph.microsoft.com/.default" };
var tenantId = "";
var clientId = "";
var clientSecret = "";
var clientSecretCredential = new ClientSecretCredential(
tenantId, clientId, clientSecret);
var graphClient = new GraphServiceClient(clientSecretCredential, scopes);
var inboxMessages = await graphClient
.Users["email"]
.MailFolders["inbox"]
.Messages
.Request()
.Expand("attachments")
.Top(20)
.GetAsync();
Console.WriteLine(inboxMessages);
Console.ReadLine();

Разрешения:

Подробнее здесь: https://stackoverflow.com/questions/739 ... in-c-sharp