System.Net.Mail.SmtpClient.Dispose C# (CSharp) Method

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

 public void sendPurchaseOrderToSupplier()
 {
     MailMessage purchaseOrderEmail = new MailMessage();
     purchaseOrderEmail.To.Add(address);
     purchaseOrderEmail.From = new MailAddress("*****@*****.**");
     purchaseOrderEmail.Subject = "Purchase Order From Williams Engraving and Specialty Supplies";
     Attachment attachment = new Attachment(path, MediaTypeNames.Application.Octet);
     purchaseOrderEmail.Attachments.Add(attachment);
     using (SmtpClient smtp = new SmtpClient())
     {
         try
         {
             smtp.Host = "smtp.gmail.com";
             smtp.Port = 587;
             smtp.EnableSsl = true;
             smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
             smtp.UseDefaultCredentials = false;
             smtp.Credentials = new NetworkCredential("*****@*****.**", "Pa$$word");
             smtp.Send(purchaseOrderEmail);
         }
         catch (SmtpException ex)
         {
             smtp.Dispose();
         }
         finally
         {
             purchaseOrderEmail.Dispose();
             smtp.Dispose();
         }
     }
 }