ASP.Net form issue after moving servers - "Failure sending mail" - asp.net

Question

After hours and hours of head scratching and not knowing WHY my site's code used to work on the old server and now on the new server it just doesn't work (changed IP of mailserver, used subdomain address for the server, changed ports, tried 25, 26, 587 and anything suggested by the server admins) I have finally stumbled through the real issue (I think) which is that the hosting requires authentication.
I have no idea how to add authentication to my old code and the support doesn't even reply to my tickets anymore. Any help is appreciated.
This is the part in the registration file which sends the activation code:
MailClass.MailGonder("info#mysite.com", TxtEMail.Text, "Activation", body, "info#mysite.com", "emailpassword", "mail.mysite.com", 587);
And this is the Mail_Class.cs file which handles the mail sending of all pages (there are other pages which also use this other than the registration page):
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Net.Mail;
using System.Net;
namespace Sngl
{
public class MailClass
{
public MailClass() { }
public static void MailGonder(string kimden, string kime, string title, string body, string senderEmail, string senderPassword, string smtpServer, int port)
{
try
{
System.Net.Mail.MailMessage MyMailMessage = new System.Net.Mail.MailMessage(kimden, kime, title, body);
MyMailMessage.IsBodyHtml = true;
MyMailMessage.Priority = System.Net.Mail.MailPriority.High;
System.Net.NetworkCredential mailAuthentication = new
System.Net.NetworkCredential(senderEmail, senderPassword);
System.Net.Mail.SmtpClient mailClient = new System.Net.Mail.SmtpClient(smtpServer, port);
mailClient.EnableSsl = false;
mailClient.UseDefaultCredentials = false;
mailClient.Credentials = mailAuthentication;
mailClient.Send(MyMailMessage);
PropertyClass.Result = true;
}
catch (Exception ex)
{
PropertyClass.Result = false;
PropertyClass.Message = ex.Message;
}
}
}
}
Error message shown is: "Failure sending mail."
No more details are given.

Answer 1

The link you gave must be for a really old posting because the example it gives uses obsolete .net classes. I've converted it to c# for you below, but i've got no idea if it will work as I've never used this stuff before.
using System;
using System.Web.Mail;
namespace Sngl
{
public class MailClass
{
public MailClass() { }
public static void MailGonder(string kimden, string kime, string title, string body, string senderEmail, string senderPassword, string smtpServer, int port)
{
try
{
var message = new MailMessage
{
From = kimden,
To = kime,
Subject = title,
Body = body
};
message.Fields["http://schemas.microsoft.com/cdo/configuration/smtpserver"] = smtpServer;
message.Fields["http://schemas.microsoft.com/cdo/configuration/smtpserverport"] = port;
message.Fields["http://schemas.microsoft.com/cdo/configuration/sendusing"] = 1;
message.Fields["http://schemas.microsoft.com/cdo/configuration/smtpauthenticate"] = 1;
message.Fields["http://schemas.microsoft.com/cdo/configuration/sendusername"] = senderEmail;
message.Fields["http://schemas.microsoft.com/cdo/configuration/sendpassword"] = senderPassword;
message.Fields["http://schemas.microsoft.com/cdo/configuration/smtpconnectiontimeout"] = 60;
SmtpMail.SmtpServer = smtpServer;
SmtpMail.Send(message);
PropertyClass.Result = true;
}
catch (Exception ex)
{
PropertyClass.Result = false;
PropertyClass.Message = ex.Message;
throw;
}
}
}
}