wp-includes/PHPMailer/PHPMailer.php:1608Create a message and send it.
bool public function send() { try { if (!$this->preSend()) { return false; } return $this->postSend(); } catch (Exception $exc) { $this->mailHeader = ''; $this->setError($exc->getMessage()); if ($this->exceptions) { throw $exc; } return false; } }Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/PHPMailer/PHPMailer.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.