diff --git a/classes/SMTPMailingQueueOriginal.php b/classes/SMTPMailingQueueOriginal.php
old mode 100755
new mode 100644
index f979958..9a7c8ca
--- a/classes/SMTPMailingQueueOriginal.php
+++ b/classes/SMTPMailingQueueOriginal.php
@@ -16,10 +16,10 @@ class SMTPMailingQueueOriginal {
 	 *
 	 * The default content type is 'text/plain' which does not allow using HTML.
 	 * However, you can set the content type of the email by using the
-	 * 'wp_mail_content_type' filter.
+	 * {@see 'wp_mail_content_type'} filter.
 	 *
 	 * The default charset is based on the charset used on the blog. The charset can
-	 * be set using the 'wp_mail_charset' filter.
+	 * be set using the {@see 'wp_mail_charset'} filter.
 	 *
 	 * @since 1.2.1
 	 *
@@ -36,7 +36,7 @@ public static function wp_mail( $to, $subject, $message, $headers = '', $attachm
 		// Compact the input, apply the filters, and extract them back out
 
 		/**
-		 * Filter the wp_mail() arguments.
+		 * Filters the wp_mail() arguments.
 		 *
 		 * @since 2.2.0
 		 *
@@ -78,6 +78,8 @@ public static function wp_mail( $to, $subject, $message, $headers = '', $attachm
 		}
 
 		// Headers
+		$cc = $bcc = $reply_to = array();
+
 		if ( empty( $headers ) ) {
 			$headers = array();
 		} else {
@@ -89,8 +91,6 @@ public static function wp_mail( $to, $subject, $message, $headers = '', $attachm
 				$tempheaders = $headers;
 			}
 			$headers = array();
-			$cc = array();
-			$bcc = array();
 
 			// If it's actually got contents
 			if ( !empty( $tempheaders ) ) {
@@ -126,7 +126,7 @@ public static function wp_mail( $to, $subject, $message, $headers = '', $attachm
 								$from_email = str_replace( '>', '', $from_email );
 								$from_email = trim( $from_email );
 
-								// Avoid setting an empty $from_email.
+							// Avoid setting an empty $from_email.
 							} elseif ( '' !== trim( $content ) ) {
 								$from_email = trim( $content );
 							}
@@ -142,7 +142,7 @@ public static function wp_mail( $to, $subject, $message, $headers = '', $attachm
 									$charset = '';
 								}
 
-								// Avoid setting an empty $content_type.
+							// Avoid setting an empty $content_type.
 							} elseif ( '' !== trim( $content ) ) {
 								$content_type = trim( $content );
 							}
@@ -153,6 +153,9 @@ public static function wp_mail( $to, $subject, $message, $headers = '', $attachm
 						case 'bcc':
 							$bcc = array_merge( (array) $bcc, explode( ',', $content ) );
 							break;
+						case 'reply-to':
+							$reply_to = array_merge( (array) $reply_to, explode( ',', $content ) );
+							break;
 						default:
 							// Add it to our grand headers array
 							$headers[trim( $name )] = trim( $content );
@@ -191,78 +194,67 @@ public static function wp_mail( $to, $subject, $message, $headers = '', $attachm
 		}
 
 		/**
-		 * Filter the email address to send from.
+		 * Filters the email address to send from.
 		 *
 		 * @since 2.2.0
 		 *
 		 * @param string $from_email Email address to send from.
 		 */
-		$phpmailer->From = apply_filters( 'wp_mail_from', $from_email );
+		$from_email = apply_filters( 'wp_mail_from', $from_email );
 
 		/**
-		 * Filter the name to associate with the "from" email address.
+		 * Filters the name to associate with the "from" email address.
 		 *
 		 * @since 2.3.0
 		 *
 		 * @param string $from_name Name associated with the "from" email address.
 		 */
-		$phpmailer->FromName = apply_filters( 'wp_mail_from_name', $from_name );
+		$from_name = apply_filters( 'wp_mail_from_name', $from_name );
+
+		$phpmailer->setFrom( $from_email, $from_name, false );
 
 		// Set destination addresses
 		if ( !is_array( $to ) )
 			$to = explode( ',', $to );
 
-		foreach ( (array) $to as $recipient ) {
-			try {
-				// Break $recipient into name and address parts if in the format "Foo <bar@baz.com>"
-				$recipient_name = '';
-				if ( preg_match( '/(.*)<(.+)>/', $recipient, $matches ) ) {
-					if ( count( $matches ) == 3 ) {
-						$recipient_name = $matches[1];
-						$recipient = $matches[2];
-					}
-				}
-				$phpmailer->AddAddress( $recipient, $recipient_name);
-			} catch ( phpmailerException $e ) {
-				continue;
-			}
-		}
-
 		// Set mail's subject and body
 		$phpmailer->Subject = $subject;
 		$phpmailer->Body    = $message;
 
-		// Add any CC and BCC recipients
-		if ( !empty( $cc ) ) {
-			foreach ( (array) $cc as $recipient ) {
-				try {
-					// Break $recipient into name and address parts if in the format "Foo <bar@baz.com>"
-					$recipient_name = '';
-					if ( preg_match( '/(.*)<(.+)>/', $recipient, $matches ) ) {
-						if ( count( $matches ) == 3 ) {
-							$recipient_name = $matches[1];
-							$recipient = $matches[2];
-						}
-					}
-					$phpmailer->AddCc( $recipient, $recipient_name );
-				} catch ( phpmailerException $e ) {
-					continue;
-				}
+		// Use appropriate methods for handling addresses, rather than treating them as generic headers
+		$address_headers = compact( 'to', 'cc', 'bcc', 'reply_to' );
+
+		foreach ( $address_headers as $address_header => $addresses ) {
+			if ( empty( $addresses ) ) {
+				continue;
 			}
-		}
 
-		if ( !empty( $bcc ) ) {
-			foreach ( (array) $bcc as $recipient) {
+			foreach ( (array) $addresses as $address ) {
 				try {
 					// Break $recipient into name and address parts if in the format "Foo <bar@baz.com>"
 					$recipient_name = '';
-					if ( preg_match( '/(.*)<(.+)>/', $recipient, $matches ) ) {
+
+					if ( preg_match( '/(.*)<(.+)>/', $address, $matches ) ) {
 						if ( count( $matches ) == 3 ) {
 							$recipient_name = $matches[1];
-							$recipient = $matches[2];
+							$address        = $matches[2];
 						}
 					}
-					$phpmailer->AddBcc( $recipient, $recipient_name );
+
+					switch ( $address_header ) {
+						case 'to':
+							$phpmailer->addAddress( $address, $recipient_name );
+							break;
+						case 'cc':
+							$phpmailer->addCc( $address, $recipient_name );
+							break;
+						case 'bcc':
+							$phpmailer->addBcc( $address, $recipient_name );
+							break;
+						case 'reply_to':
+							$phpmailer->addReplyTo( $address, $recipient_name );
+							break;
+					}
 				} catch ( phpmailerException $e ) {
 					continue;
 				}
@@ -278,7 +270,7 @@ public static function wp_mail( $to, $subject, $message, $headers = '', $attachm
 			$content_type = 'text/plain';
 
 		/**
-		 * Filter the wp_mail() content type.
+		 * Filters the wp_mail() content type.
 		 *
 		 * @since 2.3.0
 		 *
@@ -299,7 +291,7 @@ public static function wp_mail( $to, $subject, $message, $headers = '', $attachm
 		// Set the content-type and charset
 
 		/**
-		 * Filter the default wp_mail() charset.
+		 * Filters the default wp_mail() charset.
 		 *
 		 * @since 2.3.0
 		 *
@@ -309,7 +301,7 @@ public static function wp_mail( $to, $subject, $message, $headers = '', $attachm
 
 		// Set custom headers
 		if ( !empty( $headers ) ) {
-			foreach( (array) $headers as $name => $content ) {
+			foreach ( (array) $headers as $name => $content ) {
 				$phpmailer->AddCustomHeader( sprintf( '%1$s: %2$s', $name, $content ) );
 			}
 
@@ -340,7 +332,21 @@ public static function wp_mail( $to, $subject, $message, $headers = '', $attachm
 		try {
 			return $phpmailer->Send();
 		} catch ( phpmailerException $e ) {
+
+			$mail_error_data = compact( 'to', 'subject', 'message', 'headers', 'attachments' );
+			$mail_error_data['phpmailer_exception_code'] = $e->getCode();
+
+			/**
+			 * Fires after a phpmailerException is caught.
+			 *
+			 * @since 4.4.0
+			 *
+			 * @param WP_Error $error A WP_Error object with the phpmailerException message, and an array
+			 *                        containing the mail recipient, subject, message, headers, and attachments.
+			 */
+			do_action( 'wp_mail_failed', new WP_Error( 'wp_mail_failed', $e->getMessage(), $mail_error_data ) );
+
 			return false;
 		}
 	}
-}
\ No newline at end of file
+}
diff --git a/classes/SMTPMailingQueueTools.php b/classes/SMTPMailingQueueTools.php
index d178f10..d2ae6cb 100644
--- a/classes/SMTPMailingQueueTools.php
+++ b/classes/SMTPMailingQueueTools.php
@@ -204,7 +204,7 @@ public function sendTestMail() {
 		$bcc = array_filter(array_map('trim', explode(',', $data['bcc'])));
 		foreach ($bcc as $email)
 			$data['headers'][] = 'Bcc:' . $email;
-		if($data['dont_wait'])
+		if(isset($data['dont_wait']) && $data['dont_wait'])
 			$this->reallySendTestmail($data);
 		else
 			$this->writeTestmailToFile($data);
@@ -346,4 +346,4 @@ protected function getTimezoneString() {
 			// fallback to UTC
 			return 'UTC';
 	}
-}
\ No newline at end of file
+}