PostFix Bug - Urgent Bug

I have recently changed IP from my server (CWP Panel) after this operation Postfix accept always authentication like:

MailMessage mail = new MailMessage();
            SmtpClient SmtpServer = new SmtpClient("mail.myserver.com");
            mail.From = new MailAddress("contact@myserver.com", "Service Bug");
            mail.To.Add("contact@myserver.com");
            mail.Subject = "Test Email";
            mail.Body = "Hello?";
            SmtpServer.Port = 25;
            SmtpServer.Credentials = new System.Net.NetworkCredential("email@myserver.com", "anypass");
            SmtpServer.EnableSsl = false;
            SmtpServer.Send(mail);

THIS IS A CRITICAL BUG!

BUT IF USE A 587 PORT THE AUTHENTICATION RESULT FAIL

PLEASE HELP ME!

Hello.

Did you try re-build postfix? (CWP -> "Email" -> "Postfix Manager")

yes, now i have reinstalled server with new ip and bug not ppresent =)

great