Connection attempt failed error while sending mail to the Users

Question

In my project, I have implemented a Forgot password functionality where users enters his/her Email-Id ID and submits the button. Then he will receive his ID and password details on the Registered email id.

This all functionality is working fine on my local server. But when I integrated this to server, it gives me error as

A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond 74.125.68.109:587

I also tried this link but it did not helped me out and was getting the same error.

Here is my Send Mail Code:-

protected void btnSubmit_Click(object sender, EventArgs e)
    {
        DataSet ds = new DataSet();
        using (SqlConnection conn = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["DefaultCSRConnection"].ConnectionString))
        {
            conn.Open();
            SqlCommand cmd = new SqlCommand("SELECT username,password FROM tbl_User Where email= '" + txtEmail.Text.Trim() + "'", conn);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            da.Fill(ds);
            conn.Close();
            if (ds.Tables[0].Rows.Count > 0)
            {
                MailMessage Msg = new MailMessage();
                // Sender e-mail address.
                Msg.From = new MailAddress(txtEmail.Text);
                // Recipient e-mail address.
                Msg.To.Add(txtEmail.Text);
                Msg.Subject = "Password Details";
                Msg.Body = "Hi, <br/>Your login details are<br/><br/>Your Username is: " + ds.Tables[0].Rows[0]["username"] + "<br/><br/>Your Password is: " + Decrypt(ds.Tables[0].Rows[0]["password"].ToString()) + "<br/><br/>";
                Msg.IsBodyHtml = true;
                // your remote SMTP server IP.
                SmtpClient smtp = new SmtpClient();
                smtp.Host = "smtp.gmail.com";
                smtp.Port = 587;
                smtp.Credentials = new System.Net.NetworkCredential("mygmailid", "**********");
                smtp.EnableSsl = true;
                smtp.Send(Msg);
                Msg = null;
                //lbltxt.Text = "Your Password Details Sent to your mail";
                ScriptManager.RegisterStartupScript(this, this.GetType(), "alert", "alert('Your Password Details Sent to your mail');window.location ='Login.aspx';", true);
                // Clear the textbox valuess
                txtEmail.Text = "";
            }
            else
            {
                Response.Write("<script>alert('Email Id you entered does not exist');</script>");
            }
        }
    }

Please suggest what might be the issue.

STACK TRACE ERROR:-

* Exception Details: System.Net.WebException: The remote name could not be resolved: 'smtp.gmail.com' Source Error: Line 63: smtp.Credentials = new System.Net.NetworkCredential("mygmailid", "************"); Line 64: smtp.EnableSsl = true; Line 65: smtp.Send(Msg); Line 66: Msg = null; Line 67: //lbltxt.Text = "Your Password Details Sent to your mail"; Source File: d:\\RBLBank\\NGOManagement-CSR\\CSRProject\\ForgotPassword.aspx.cs Line: 65 Stack Trace: [WebException: The remote name could not be resolved: 'smtp.gmail.com'] System.Net.ServicePoint.GetConnection(PooledStream PooledStream, Object owner, Boolean async, IPAddress& address, Socket& abortSocket, Socket& abortSocket6, Int32 timeout) +7895034 System.Net.PooledStream.Activate(Object owningObject, Boolean async, Int32 timeout, GeneralAsyncDelegate asyncCallback) +7895462 System.Net.PooledStream.Activate(Object owningObject, GeneralAsyncDelegate asyncCallback) +36 System.Net.ConnectionPool.GetConnection(Object owningObject, GeneralAsyncDelegate asyncCallback, Int32 creationTimeout) +2868427 System.Net.Mail.SmtpConnection.GetConnection(ServicePoint servicePoint) +286 System.Net.Mail.SmtpClient.Send(MailMessage message) +1553 [SmtpException: Failure sending mail.] System.Net.Mail.SmtpClient.Send(MailMessage message) +2187943 CSRProject.ForgotPassword.btnSubmit_Click(Object sender, Eve ntArgs e) in d:\\RBLBank\\NGOManagement-CSR\\CSRProject\\ForgotPassword.aspx.cs:65 System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +154 System.Web.UI.Page.ProcessRequestMain(Boolean >includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3707 *