sending mail through windows application problem

You are not using network credential. That's the error is occuring just check out the credential as follow.
SmtpClient serverobj = new SmtpClient();
        serverobj.Credentials = new NetworkCredential("gmailid","gmailpwd");
        serverobj.Port = 25;
        serverobj.Host = "Smtp.gmail.com";
        serverobj.EnableSsl = true;
       

this is my code for sending mail through gmail using windows application. I have been getting error. also i have tried with attaching file.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text.RegularExpressions;
using System.Windows.Forms;
using System.Net.Mail;
using System.Net.Mime;

namespace MailApplication
{
    public partial class frMailSendingForm : Form
    {
        MailMessage msg;
        static bool mailSent = false;
        public frMailSendingForm()
        {
            InitializeComponent();
        }

        private void txtFrom_TextChanged(object sender, EventArgs e)
        {

        }

        private void txtTo_TextChanged(object sender, EventArgs e)
        {

        }

        private void btnSend_Click(object sender, EventArgs e)
        {
            SmtpClient client = new SmtpClient("smtp.gmail.com");
            string userState = "test message";
            try
            {
                MailMessage From = new MailMessage("[email protected]", "[email protected]", "Hello", "This is a test message");
                MailAddress To = new MailAddress(txtTo.Text.Trim());
                msg = new MailMessage();

                msg.To.Add(txtTo.Text.Trim());

                msg.From = new MailAddress("[email protected]");
                msg.Body = rtxtMsg.Text.Trim();

                msg.BodyEncoding = System.Text.Encoding.UTF8;

                client.SendCompleted += new SendCompletedEventHandler(client_SendCompleted);
                client.SendAsync(msg, userState);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
        void client_SendCompleted(object sender, AsyncCompletedEventArgs e)
        {
            try
            {
                if (e.Cancelled)
                {
                    string cancelled = string.Format("Send canceled");
                    MessageBox.Show(cancelled);
                }
                if (e.Error != null)
                {
                    string error = string.Format(e.Error.ToString());
                    MessageBox.Show(error);
                }
                else
                {
                    MessageBox.Show("Message Sent Successfully");
                }
                mailSent = true;
                msg.Dispose();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error");
            }
        }
        private void SendCompletedCallback(object sender, AsyncCompletedEventArgs e)
        {
            string token = (string)e.UserState;

            if (e.Cancelled)
            {
                MessageBox.Show("[{0}] Send canceled", token);
            }
            if (e.Error != null)
            {
            }
            else
            {
                MessageBox.Show("Message sent");
            }
            mailSent = true;
        }

        private void txtSubject_TextChanged(object sender, EventArgs e)
        {
            txtFrom.Text = txtSubject.Text.Trim();
        }

        static void AttachmentFromFile()
        {
            MailMessage mail = new MailMessage();

            mail.From = new MailAddress("[email protected]");
            mail.To.Add("[email protected]");

            mail.Subject = "This is a test mail";
            mail.Body = "this is a test mail";

            mail.Attachments.Add(new Attachment("C:\\Users\\Avinash\\Documents\\Desktop\\gopi sir mail id.txt"));

            SmtpClient smtp = new SmtpClient("smtp.gmail.com");
            smtp.Credentials = new System.Net.NetworkCredential("[email protected]", "mypassword");
            smtp.Send(mail);
           
       
        }
    }
}
       
Please help me with this

For code just check out the articles on right hand side of this thread. It will help you else upload u r code then we can check it.

i checked with credentials and again the same error.
Please help me with the code. Also i wanted code for attaching files and sending mail via the same windows application.

It's might be cause of your credential please check out the credential you are using.