Mailkit authenticating self hosted email with my exchange server?

Question

Essentially, I have a local mail server with exchange and active directory and etc.. I'm trying to authenticate an email with Mailkit in C# but I get an authentication error every single time. I've tried many different ways of using client#Authenticate by using "int\name", "password" or "name", "password" or "address", "password" etc. Here's my code:

public Email()
    {

        var message = new MimeMessage();
        message.From.Add(new MailboxAddress("", "[email protected]"));
        message.To.Add(new MailboxAddress("", "[email protected]"));
        message.Subject = "test email";

        message.Body = new TextPart("plain")
        {
            Text = @"test"
        };

        var client = new SmtpClient();
        client.Connect("my.mailserver.com", 25, MailKit.Security.SecureSocketOptions.StartTls);
        client.Authenticate("[email protected]", "mypassword");
        client.Send(message);

        client.Disconnect(true);
    }

Answer 1

Fixed it everyone. Hopefully someone can benefit from this in the future.

Fixed it by using port 587 instead of 25, and also by using fqdn\username