SmtpException Message: Failure sending mail.

Hello,
I have problem sending SMTP Emil The exception is 
Failure sending mail. ---> System.ComponentModel.Win32Exception: The credentials supplied to the package were not recognized at System.Net.NTAuthentication.GetOutgoingBlob(Byte[] incomingBlob, Boolean throwOnError, SecurityStatus& statusCode) at System.Net.NTAuthentication.GetOutgoingBlob(String incomingBlob) at System.Net.Mail.SmtpNtlmAuthenticationModule.Authenticate(String challenge, NetworkCredential credential, Object sessionCookie, String spn, ChannelBinding channelBindingToken) at System.Net.Mail.SmtpConnection.GetConnection(ServicePoint servicePoint) at System.Net.Mail.SmtpClient.Send(MailMessage message) --- End of inner exception stack trace --- at System.Net.Mail.SmtpClient.Send(MailMessage message)

On first look you think that's this is invalid username and password, but actully i have success send email on my test machine but on the ...