MAIL SERVER

http://www.diaryofaninja.com/blog/2009/10/02/sending-encrypted-email-with-c

http://stackoverflow.com/questions/12412054/sending-emails-that-requires-a-secure-connection

http://www.codeproject.com/Articles/41727/An-S-MIME-Library-for-Sending-Signed-and-Encrypted

//Rijndael algorithm.
 
private void EncryptFile(string inputFile, string outputFile)
{
 
  try
  {
  string password = @"myKey123"; // Your Key Here
  UnicodeEncoding UE = new UnicodeEncoding();
  byte[] key = UE.GetBytes(password);
 
  string cryptFile = outputFile;
  FileStream fsCrypt = new FileStream(cryptFile, FileMode.Create);
 
  RijndaelManaged RMCrypto = new RijndaelManaged();
 
  CryptoStream cs = new CryptoStream(fsCrypt,
  RMCrypto.CreateEncryptor(key, key),
  CryptoStreamMode.Write);
 
  FileStream fsIn = new FileStream(inputFile, FileMode.Open);
 
  int data;
  while ((data = fsIn.ReadByte()) != -1)
  cs.WriteByte((byte)data);
 
 
  fsIn.Close();
  cs.Close();
  fsCrypt.Close();
  }
  catch
  {
  MessageBox.Show("Encryption failed!", "Error");
  }
}




private void DecryptFile(string inputFile, string outputFile)
{
 
  {
  string password = @"myKey123"; // Your Key Here
 
  UnicodeEncoding UE = new UnicodeEncoding();
  byte[] key = UE.GetBytes(password);
 
  FileStream fsCrypt = new FileStream(inputFile, FileMode.Open);
 
  RijndaelManaged RMCrypto = new RijndaelManaged();
 
  CryptoStream cs = new CryptoStream(fsCrypt,
  RMCrypto.CreateDecryptor(key, key),
  CryptoStreamMode.Read);
 
  FileStream fsOut = new FileStream(outputFile, FileMode.Create);
 
  int data;
  while ((data = cs.ReadByte()) != -1)
  fsOut.WriteByte((byte)data);
 
  fsOut.Close();
  cs.Close();
  fsCrypt.Close();
 
  }
}