An error on sending mail in SSIS usign Script Task

Using the following visual C# codes to send a hotmail mail, got the error, then changed the port number from 25 to 587 it works!

 using System;
using System.Data;
using Microsoft.SqlServer.Dts.Runtime;
using System.Windows.Forms;
using System.Net;
using System.Net.Mail;
namespace ST_41027be1cfb14c29a9b05c97e79b0f8c.csproj
{
    [System.AddIn.AddIn("ScriptMain", Version = "1.0", Publisher = "", Description = "")]
    public partial class ScriptMain : Microsoft.SqlServer.Dts.Tasks.ScriptTask.VSTARTScriptObjectModelBase
    {

        #region VSTA generated code
        enum ScriptResults
        {
            Success = Microsoft.SqlServer.Dts.Runtime.DTSExecResult.Success,
            Failure = Microsoft.SqlServer.Dts.Runtime.DTSExecResult.Failure
        };
        #endregion
       
              public void Main()
        {
            MailMessage msg = new MailMessage ("cxulz@hotmail.com","cxulz@hotmail.com", "This from C#","hey, buddy");
            SmtpClient client =new SmtpClient ("smtp.live.com",587);
            client.EnableSsl =true;
            client.DeliveryMethod =SmtpDeliveryMethod.Network;
            client.Credentials =new NetworkCredential("cxulz@hotmail.com","xxxxxxx1");
            client.Send(msg);
            Dts.TaskResult = (int)ScriptResults.Success;
        }
    }
}

================
see the differences with the VB codes for the same functionality

Imports System
Imports System.Data
Imports System.Math
Imports Microsoft.SqlServer.Dts.Runtime
Imports System.Net
Imports System.Net.Mail
_
_
Partial Public Class ScriptMain
 Inherits Microsoft.SqlServer.Dts.Tasks.ScriptTask.VSTARTScriptObjectModelBase
 Enum ScriptResults
  Success = Microsoft.SqlServer.Dts.Runtime.DTSExecResult.Success
  Failure = Microsoft.SqlServer.Dts.Runtime.DTSExecResult.Failure
 End Enum

    Public Sub Main()
        Dim msg As New MailMessage("cxulz@hotmail.com", "cxulz@hotmail.com", "This from VB", "hey, buddy")
        Dim client As New SmtpClient("smtp.live.com", 587)
        client.EnableSsl = True
        client.DeliveryMethod = SmtpDeliveryMethod.Network
        client.Credentials = New NetworkCredential("cxulz@hotmail.com", "nanjing1")
        client.Send(msg)
        Dts.TaskResult = ScriptResults.Success
    End Sub
End Class