使用AppID和APPSecret验证SmtpClient，而不传递用户名和密码

问题描述

我在c＃控制台应用程序中具有以下SharePoint CSOM代码，以使用office 365管理员用户名和密码发送电子邮件：-

 static private void sendemail(ClientContext context,string subject,string body,FieldUserValue[] to,string username,securestring passWord)
        {

            try
            {
                using (MailMessage mail = new MailMessage())
                {

                    mail.From = new MailAddress("sharepoint@***.com");
                    mail.Subject = subject;
                    mail.IsBodyHtml = true;
                    SmtpClient client = new SmtpClient("***-com.mail.protection.outlook.com",25);
                    client.DeliveryMethod = SmtpDeliveryMethod.Network;
                    client.UseDefaultCredentials = false;
                    client.Credentials = new NetworkCredential(username,passWord);
                    client.EnableSsl = true;
                    mail.Body = body;
                    string approvalemailTo = "";

                    foreach (var t in to)
                    {
                        mail.To.Add(t.Email);
                        approvalemailTo = approvalemailTo + t.Email + ";";
                    }
                    client.Send(mail);
                    }
            }


            catch (Exception e)
            {

                   

            }

        }

但是为了使我的代码更安全，我如何使用AppID和APPSecret而不是通过用户名和密码来验证SmtpClient？

谢谢

解决方法

您的代码只是System.net.mail程序集中的标准SMTP代码，它不依赖于Sharepoint CSOM。如果要在SMTP中使用现代身份验证，则无法使用客户端凭据流https://docs.microsoft.com/en-us/azure/active-directory/develop/v2-oauth2-client-creds-grant-flow按照

此功能公告适用于交互式应用程序，以为IMAP和SMTP启用OAuth。目前，尚无计划使用客户端凭据流为非交互式应用程序启用IMAP和SMTP OAuth。为此，我们建议使用我们的Graph API。

https://techcommunity.microsoft.com/t5/exchange-team-blog/announcing-oauth-2-0-support-for-imap-and-smtp-auth-protocols-in/ba-p/1330432

如果要执行此操作，则需要使用Microsoft Graph API，这对您而言很简单。如果您要坚持使用SMTP并使用现代身份验证，则需要使用支持它的MailKit https://github.com/jstedfast/MailKit之类的东西，例如使用MSAL和Interactive Auth的简单示例

        String ClientId = "20773535-6b8f-4f3d-8f0e-4b7710d79afe";
        string UserName = "[email protected]";
        string scope = "https://outlook.office.com/SMTP.Send";
        string redirectUri = "msal20773535-6b8f-4f3d-8f0e-4b7710d79afe://auth";
        string From = "[email protected];
        String To = "[email protected]";
        String SMTPServer = "smtp.office365.com";
        Int32 SMTPPort = 587;

        PublicClientApplicationBuilder pcaConfig = PublicClientApplicationBuilder.Create(ClientId)
         .WithAuthority(AadAuthorityAudience.AzureAdMultipleOrgs);

        pcaConfig.WithRedirectUri(redirectUri);
        var TokenResult = await pcaConfig.Build().AcquireTokenInteractive(new[] { scope })
         .WithPrompt(Prompt.Never)
         .WithLoginHint(UserName).ExecuteAsync();


        var message = new MimeMessage();
        message.From.Add(MailboxAddress.Parse(From));
        message.To.Add(MailboxAddress.Parse(To));
        message.Subject = "Test";
        message.Body = new TextPart("plain")
        {
            Text = @"Hey Joe"
        };
        using (var client = new SmtpClient())
        {
            client.Connect(SMTPServer,SMTPPort,SecureSocketOptions.StartTls);
            var oauth2 = new SaslMechanismOAuth2(UserName,TokenResult.AccessToken);
            client.Authenticate(oauth2);

            await client.SendAsync(message);
            client.Disconnect(true);
        }