Authenticated mail sending not working in .NET - asp.net

Question

I have a script sending mail from my .net application.
My hosting provider requires the emails to be authenticated if I don't want to cause delays in receiving them (currently delay is almost a day from sending).
I have build mail sending script with authentication but it doesn't work - it doesn't produce any error or exception but the emails are still not received instantly.
In the other hand similar script made in classic asp works and I receive mails instantly.
Am I missing something?
This is asp script (which works):
<%
Set objEmail = CreateObject("CDO.Message")
objEmail.From = "sender#mydomain.com"
objEmail.To = "recipient#gmail.com"
objEmail.Subject = "Test Mail"
objEmail.Textbody = "Test Mail"
objEmail.Configuration.Fields.Item ("http://schemas.microsoft.com/cdo/configuration/sendusing") = 2
objEmail.Configuration.Fields.Item ("http://schemas.microsoft.com/cdo/configuration/smtpserver") = "mail.mydomain.com"
objEmail.Configuration.Fields.Item ("http://schemas.microsoft.com/cdo/configuration/smtpserverport") = 25
objEmail.Configuration.Fields.Item ("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate") = "1"
objEmail.Configuration.Fields.Item ("http://schemas.microsoft.com/cdo/configuration/sendusername") = "myusername"
objEmail.Configuration.Fields.Item ("http://schemas.microsoft.com/cdo/configuration/sendpassword") = "mypassword"
objEmail.Configuration.Fields.Update
objEmail.Send
If Not err.number=0 Then
Response.write "ERROR: " & err.Description
err.Clear
end if
%>
This is .NEt (which doesn't work):
public static void SendEmail(string senderName, string senderEmail, string recipient, string comments, string subject, bool inTemplate)
{
MailAddress from = new MailAddress(senderEmail);
MailAddress to = new MailAddress(recipient);
MailMessage mail = new MailMessage(from, to);
mail.ReplyToList.Add(senderEmail);
mail.Subject = subject;
mail.IsBodyHtml = true;
mail.Body = comments;
Configuration configurationFile = WebConfigurationManager.OpenWebConfiguration(HttpContext.Current.Request.ApplicationPath);
MailSettingsSectionGroup mailSettings = configurationFile.GetSectionGroup("system.net/mailSettings") as MailSettingsSectionGroup;
NetworkCredential basicCredentials = new NetworkCredential(mailSettings.Smtp.Network.UserName, mailSettings.Smtp.Network.Password);
SmtpClient smtpClient = new SmtpClient();
smtpClient.Host = mailSettings.Smtp.Network.Host;
smtpClient.Port = mailSettings.Smtp.Network.Port;
smtpClient.UseDefaultCredentials = false;
smtpClient.Credentials = basicCredentials;
try
{
smtpClient.Send(mail);
}
catch (Exception ex)
{
throw ex;
}
}
These are my web.config settings:
<system.net>
<mailSettings>
<smtp>
<network host="mail.mydomain.com" userName="myusername" password="mypassword" port="25" />
</smtp>
</mailSettings>
</system.net>
The web.config settings are correct but even if I input server settings manually into the class - it doesn't work.
Thanks

Answer 1

Try this:
MailMessage mailMsg = new MailMessage();
mailMsg.To.Add("test#hotmail.com");
// From
MailAddress mailAddress = new MailAddress("you#hotmail.com");
mailMsg.From = mailAddress;
// Subject and Body
mailMsg.Subject = "subject";
mailMsg.Body = "body";
// Init SmtpClient and send on port 587 in my case. (Usual=port25)
SmtpClient smtpClient = new SmtpClient("mailserver", 587);
System.Net.NetworkCredential credentials =
new System.Net.NetworkCredential("username", "password");
smtpClient.Credentials = credentials;
smtpClient.Send(mailMsg);

Answer 2

It turned out that the problem was at the hosting provider side. Not sure what they did but it eventually started to work.