Refactor some code into overridable methods.

This should make the transport a little more extensibility friendly.

lib/Cake/Network/Email/SmtpTransport.php

@@ -153,38 +153,65 @@ protected function _auth() {
 	}
 
 /**
- * Send emails
+ * Prepares the `MAIL FROM` SMTP command.
  *
- * @return void
- * @throws SocketException
+ * @param string $email The email address to send with the command.
+ * @return string
  */
-	protected function _sendRcpt() {
+	protected function _prepareFromCmd($email) {
+		return 'MAIL FROM:<' . $email . '>';
+	}
+
+/**
+ * Prepares the `RCPT TO` SMTP command.
+ *
+ * @param string $email The email address to send with the command.
+ * @return string
+ */
+	protected function _prepareRcptCmd($email) {
+		return 'RCPT TO:<' . $email . '>';
+	}
+
+/**
+ * Prepares the `from` email address.
+ *
+ * @return array
+ */
+	protected function _prepareFromAddress() {
 		$from = $this->_cakeEmail->returnPath();
 		if (empty($from)) {
 			$from = $this->_cakeEmail->from();
 		}
-		$this->_smtpSend('MAIL FROM:<' . key($from) . '>');
+		return $from;
+	}
 
+/**
+ * Prepares the recipient email addresses.
+ *
+ * @return array
+ */
+	protected function _prepareRecipientAddresses() {
 		$to = $this->_cakeEmail->to();
 		$cc = $this->_cakeEmail->cc();
 		$bcc = $this->_cakeEmail->bcc();
-		$emails = array_merge(array_keys($to), array_keys($cc), array_keys($bcc));
-		foreach ($emails as $email) {
-			$this->_smtpSend('RCPT TO:<' . $email . '>');
-		}
+		return array_merge(array_keys($to), array_keys($cc), array_keys($bcc));
 	}
 
 /**
- * Send Data
+ * Prepares the message headers.
  *
- * @return void
- * @throws SocketException
+ * @return array
  */
-	protected function _sendData() {
-		$this->_smtpSend('DATA', '354');
+	protected function _prepareMessageHeaders() {
+		return $this->_cakeEmail->getHeaders(array('from', 'sender', 'replyTo', 'readReceipt', 'to', 'cc', 'subject'));
+	}
 
-		$headers = $this->_cakeEmail->getHeaders(array('from', 'sender', 'replyTo', 'readReceipt', 'to', 'cc', 'subject'));
-		$headers = $this->_headersToString($headers);
+/**
+ * Prepares the message body.
+ *
+ * @return string
+ */
+	protected function _prepareMessage() {
 		$lines = $this->_cakeEmail->message();
 		$messages = array();
 		foreach ($lines as $line) {
@@ -194,7 +221,37 @@ protected function _sendData() {
 				$messages[] = $line;
 			}
 		}
-		$message = implode("\r\n", $messages);
+		return implode("\r\n", $messages);
+	}
+
+/**
+ * Send emails
+ *
+ * @return void
+ * @throws SocketException
+ */
+	protected function _sendRcpt() {
+		$from = $this->_prepareFromAddress();
+		$this->_smtpSend($this->_prepareFromCmd(key($from)));
+
+		$emails = $this->_prepareRecipientAddresses();
+		foreach ($emails as $email) {
+			$this->_smtpSend($this->_prepareRcptCmd($email));
+		}
+	}
+
+/**
+ * Send Data
+ *
+ * @return void
+ * @throws SocketException
+ */
+	protected function _sendData() {
+		$this->_smtpSend('DATA', '354');
+
+		$headers = $this->_headersToString($this->_prepareMessageHeaders());
+		$message = $this->_prepareMessage();
+
 		$this->_smtpSend($headers . "\r\n\r\n" . $message . "\r\n\r\n\r\n.");
 		$this->_content = array('headers' => $headers, 'message' => $message);
 	}