Index: src/wp-includes/pluggable.php
===================================================================
--- src/wp-includes/pluggable.php	(revision 34218)
+++ src/wp-includes/pluggable.php	(working copy)
@@ -534,6 +534,18 @@
 	try {
 		return $phpmailer->Send();
 	} catch ( phpmailerException $e ) {
+
+		$mail_error_data = compact( $to, $subject, $message, $headers, $attachments );
+		/**
+		 * Fires after a phpmailerException is caught
+		 *
+		 * @since 4.4.0
+		 *
+		 * @param WP_Error A WP_Error object with the phpmailerException code, message and an array
+		 *				   containing the mail recipient, subject, message, headers and attachments
+		 */
+ 		do_action( 'wp_mail_failed', new WP_Error( $e->getCode(), $e->getMessage(), $mail_error_data ) );
+
 		return false;
 	}
 }