20.6 Mail Sender: Using the SMTP Agent

This example program sends an e-mail message using the SMTP agent class.

20.6.1 Code and Explanation

Here is a portion of code followed by comments explaining key lines.

try {
  RWISmtpAgent agent("SMTP_mail_server");                    // 1

  RWSocketPortal sPortal = agent.send("From", "To");         // 2

  RWCString mailContent;
  .
  . 
  .
// Construct the mailContent
  .
  .
  .
  sPortal.sendAtLeast(mailContent);                          // 3

  RWBoolean dataClosed = agent.dataClose();                  // 4
}
catch (const RWxmsg& msg) {                                  
  cout << "ERROR: " << msg.why() << endl;
}

`//1`	Constructs an *RWISmtpAgent* object that connects to an SMTP mail server.
`//2`	Opens a data connection with the SMTP server. The method returns an *RWIOUResult* with a redeemable *RWSocketPortal*, which is immediately redeemed. The `sPortal` is then used to complete the mail-body portion of the protocol transfer.
`//3`	Uses the `sPortal` to send the mail content.
`//4`	Writes the mail-body termination sequence `<period><carriage return><new line>`, which indicates the end of the mail message. The `dataClose()` method returns an *RWIOUResult* with a redeemable *RWBoolean. By assigning the result of the method to the RWBoolean* object `dataClosed`, the execution thread is blocked until the actual result becomes available. This is one way of redeeming an *RWIOUResult* object. Also note that the SMTP protocol requires the `dataClose()` method be called for each data transfer session.

20.6.2 Further Discussion

This example demonstrates one method of redeeming an RWIOUResult object. For other methods, please refer to Chapter 19 and Section 20.4. The application determines which way needs to apply.