使用C＃SmtpClient发送消息

Question

我对同一邮件发送进行了两种实现：

//MailKit.Net.Smtp.SmtpClient
--------------------------------------------------------------------------------------
MailKit.Net.Smtp.SmtpClient smtp;
var message = new MimeMessage();

message.From.Add(new MailboxAddress("Test sender", "sender@domain.com"));
message.To.Add(new MailboxAddress("Test Recipiment", "recipient@domain.com"));
message.Subject = "My subject";         
message.Body = new TextPart("plain")
{
    Text = "my body"
};
smtp = new MailKit.Net.Smtp.SmtpClient();
smtp.Connect("mail.domain.com","25",false);
smtp.Authenticate("sender", "MyPassword");

smtp.Send(message);
smtp.Disconnect(true);
smtp.Dispose();

//System.Net.Mail.SmtpClient            
--------------------------------------------------------------------------------------
SmtpClient smtp = new SmtpClient("mail.domain.com","25");
smtp.EnableSsl = false;
smtp.UseDefaultCredentials = false;

MailAddress fromMailAdd;
try
{
    fromMailAdd = new MailAddress("sender@domain.com");
}
MailMessage mailMessage = new MailMessage
{
    From = fromMailAdd,
    IsBodyHtml = false,
    Body = "my body",
    Subject = "My subject",
};
mailMessage.To.Add(new MailAddress("recipient@domain.com"));

smtp.Credentials = new NetworkCredential("sender", "MyPassword");
smpt.Send(mailMessage);

MailKit实现正在运行System.Net.Mail无法运行。它得到"Mailbox name not allowed. The server response was: authentication is required"

我查看了MailKit SmtpClient的代码，其身份验证执行以下操作：

    var saslUri = new Uri ($"smtp://{uri.Host}");
    AuthenticationException authException = null;
    SmtpResponse response;
    SaslMechanism sasl;
    bool tried = false;
    string challenge;
    string command;

    foreach (var authmech in SaslMechanism.AuthMechanismRank) {
        if (!AuthenticationMechanisms.Contains (authmech))
            continue;

        if ((sasl = SaslMechanism.Create (authmech, saslUri, encoding, credentials)) == null)
            continue;

        tried = true;

        cancellationToken.ThrowIfCancellationRequested ();

        // send an initial challenge if the mechanism supports it
        if (sasl.SupportsInitialResponse) {
            challenge = sasl.Challenge (null);
            command = string.Format ("AUTH {0} {1}", authmech, challenge);
        } else {
            command = string.Format ("AUTH {0}", authmech);
        }

        response = await SendCommandAsync (command, doAsync, cancellationToken).ConfigureAwait (false);

        if (response.StatusCode == SmtpStatusCode.AuthenticationMechanismTooWeak)
            continue;

        SaslException saslException = null;

        try {
            while (!sasl.IsAuthenticated) {
                if (response.StatusCode != SmtpStatusCode.AuthenticationChallenge)
                    break;

                challenge = sasl.Challenge (response.Response);
                response = await SendCommandAsync (challenge, doAsync, cancellationToken).ConfigureAwait (false);
            }

            saslException = null;
        } catch (SaslException ex) {
            // reset the authentication state
            response = await SendCommandAsync (string.Empty, doAsync, cancellationToken).ConfigureAwait (false);
            saslException = ex;
        }

        if (response.StatusCode == SmtpStatusCode.AuthenticationSuccessful) {
            if (sasl.NegotiatedSecurityLayer)
                await EhloAsync (doAsync, cancellationToken).ConfigureAwait (false);
            authenticated = true;
            OnAuthenticated (response.Response);
            return;
        }

        var message = string.Format ("{0}: {1}", (int) response.StatusCode, response.Response);
        Exception inner;

        if (saslException != null)
            inner = new SmtpCommandException (SmtpErrorCode.UnexpectedStatusCode, response.StatusCode, response.Response, saslException);
        else
            inner = new SmtpCommandException (SmtpErrorCode.UnexpectedStatusCode, response.StatusCode, response.Response);

        authException = new AuthenticationException (message, inner);
    }

    if (tried)
        throw authException ?? new AuthenticationException ();

    throw new NotSupportedException ("No compatible authentication mechanisms found.");

凭据与.Net Mail客户端中使用的凭据是相同的NetworkCredentials类。

是否可以让.net Mail客户端执行相同类型的身份验证？

编辑： 无法更改邮件服务器本身上的内容