Can't send email with proxy server - vb.net

Question

I'm having a problem inside work, trying to send an email.
I think this is because we use a Proxy Server, however I can't find anyway of programming a proxy into VB.net, any helpers?
I keep getting the following error:
System.Net.Mail.SmtpException: Failure sending mail. ---> System.Net.WebException: Unable to connect to the remote server ---> System.Net.Sockets.SocketException: No connection could be made because the target machine actively refused it 173.194.66.109:25
at System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress)
at System.Net.ServicePoint.ConnectSocketInternal(Boolean connectFailure, Socket s4, Socket s6, Socket& socket, IPAddress& address, ConnectSocketState state, IAsyncResult asyncResult, Exception& exception)
--- End of inner exception stack trace ---
at System.Net.ServicePoint.GetConnection(PooledStream PooledStream, Object owner, Boolean async, IPAddress& address, Socket& abortSocket, Socket& abortSocket6)
at System.Net.PooledStream.Activate(Object owningObject, Boolean async, GeneralAsyncDelegate asyncCallback)
at System.Net.PooledStream.Activate(Object owningObject, GeneralAsyncDelegate asyncCallback)
at System.Net.ConnectionPool.GetConnection(Object owningObject, GeneralAsyncDelegate asyncCallback, Int32 creationTimeout)
at System.Net.Mail.SmtpConnection.GetConnection(ServicePoint servicePoint)
at System.Net.Mail.SmtpTransport.GetConnection(ServicePoint servicePoint)
at System.Net.Mail.SmtpClient.GetConnection()
at System.Net.Mail.SmtpClient.Send(MailMessage message)
--- End of inner exception stack trace ---
at System.Net.Mail.SmtpClient.Send(MailMessage message)
at SENpic.Email.butSendEmail_Click(Object sender, EventArgs e) in C:\Users\Graham\Documents\Visual Studio 2010\Projects\Email Project\EmailTest\Email.vb:line 28
Here is the code:
Try
Dim Smtp_Server As New SmtpClient
Dim e_mail As New MailMessage()
Smtp_Server.UseDefaultCredentials = False
Smtp_Server.Credentials = New Net.NetworkCredential("mymail#gmail.com", "password")
Smtp_Server.Port = 25 '587
Smtp_Server.EnableSsl = True
Smtp_Server.Host = "smtp.gmail.com"
e_mail = New MailMessage()
e_mail.From = New MailAddress(txtEmailFrom.Text, "SENpic CSP")
e_mail.To.Add("fred2000#aol.com")
e_mail.Subject = txtEmailSubject.Text
e_mail.IsBodyHtml = False
e_mail.Body = txtEmailMessage.Text
Smtp_Server.Send(e_mail)
MsgBox("Your email has been sent", MsgBoxStyle.Information + MsgBoxStyle.OkOnly, "EMail...")
Catch error_t As Exception
WriteToLogFile("Email: ", error_t.ToString)
MsgBox(error_t.ToString)
End Try
Any help is much appreciated.
Thanks
Graham