Attempt was made to access a socket in a way forbidden by its access permissions

Question

I'm using smtp google's server to send a email through my contact form..In local server it works fine but in web server it shows this error.First ,I've used port number 587 which gives error "Security Exception" and error was on the line using (SmtpClient smtp = new SmtpClient(smtpAddress, portNumber)), but I've changed port to 25 and it gives this new error on the line .

smtp.Send(mail);

Description:

An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details:

System.Net.Sockets.SocketException: An attempt was made to access a socket in a way forbidden by its access permissions 74.125.206.108:25

My code is:

protected void send_Click(object sender, EventArgs e)
{
    string smtpAddress = "smtp.gmail.com";
    int portNumber = 25;
    bool enableSSL = true;

    string emailfrom = "[email protected]";
    string password = "******";
    string subject = "Contact Form Data";
    string emailto = "[email protected]";
    string name = n.Value;       
    string useremail = em.Value;
    string phone = tel.Value;
    string dept = dep.Value;
    string dest = des.Value;
    string adu = ad.Value;

    string msg = mes.Value;
    string body = "Name: " + name + " ;" + " Email: " + useremail + " ;" + "Telephone: " + phone + " ;" + " Departure Place: " + dept + " ;" + "Destination Place: " + dest + " ;" + " Adults: " + adu + " ;" + " ;" + "Children: " + chil + " ;" + "Message: " + msg + " ;";

    using (MailMessage mail = new MailMessage())
    {
        mail.From = new MailAddress(emailfrom);
        mail.To.Add(emailto);
        mail.Subject = subject;
        mail.Body = body;
        mail.IsBodyHtml = true;

        using (SmtpClient smtp = new SmtpClient(smtpAddress, portNumber))
        {
            smtp.Credentials = new NetworkCredential(emailfrom, password);
            smtp.EnableSsl = enableSSL;
            smtp.Send(mail);
        }
    }
}

Stack Trace

[SocketException (0x271d): An attempt was made to access a socket in a way forbidden by its access permissions 74.125.206.108:25] System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress) +208 System.Net.ServicePoint.ConnectSocketInternal(Boolean connectFailure, Socket s4, Socket s6, Socket& socket, IPAddress& address, ConnectSocketState state, IAsyncResult asyncResult, Exception& exception) +464

[WebException: Unable to connect to the remote server] System.Net.ServicePoint.GetConnection(PooledStream PooledStream, Object owner, Boolean async, IPAddress& address, Socket& abortSocket, Socket& abortSocket6) +6662436 System.Net.PooledStream.Activate(Object owningObject, Boolean async, GeneralAsyncDelegate asyncCallback) +307 System.Net.PooledStream.Activate(Object owningObject, GeneralAsyncDelegate asyncCallback) +19 System.Net.ConnectionPool.GetConnection(Object owningObject, GeneralAsyncDelegate asyncCallback, Int32 creationTimeout) +324 System.Net.Mail.SmtpConnection.GetConnection(ServicePoint servicePoint) +141 System.Net.Mail.SmtpTransport.GetConnection(ServicePoint servicePoint) +170 System.Net.Mail.SmtpClient.GetConnection() +44 System.Net.Mail.SmtpClient.Send(MailMessage message) +1554

[SmtpException: Failure sending mail.] System.Net.Mail.SmtpClient.Send(MailMessage message) +1906 Contact.send_Click(Object sender, EventArgs e) in \smb-whst-www02\whst_www02$\ff8b1b\user\medviewair.uk\web\Contact.aspx.cs:51 System.Web.UI.WebControls.Button.OnClick(EventArgs e) +9628462 System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +103 System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10 System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13 System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +35 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1724

Answer 1

After Windows Update, some ports are reserved by Windows and applications cannot bind to these ports. please check this command

netsh interface ipv4 show excludedportrange protocol=tcp