Cant send via c sharp code via internet access through proxy server at college

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C#

Outlook

email

exceptions

I have to send an email via hotmail in c# wpf application.I am using internet at college which uses a proxy server .i am using the following code

  MailMessage message = new MailMessage();
            message.From = new MailAddress(textBox4.Text);
            message.Subject = textBox2.Text;
            message.Body = textBox3.Text;
           

            SmtpClient client = new SmtpClient();
            client.Credentials = new NetworkCredential(textBox4.Text, textBox5.Text);
            client.Host = "smtp-mail.outlook.com";
            client.Port = 25;
            client.EnableSsl = true;
            
            try
            {
                client.Send(message);
            }
            catch (Exception exp)
            {
                MessageBox.Show(exp.Message.ToString());
             Application.Exit();
            }
            finally
            {
                MessageBox.Show("Email Sent", "Success");
}

but i always get System.Net.WebException remote name could not be resolved ..can any one help me????