wp-includes/PHPMailer/Exception.php:36Prettify error message output.
string public function errorMessage() { return '<strong>' . htmlspecialchars($this->getMessage(), ENT_COMPAT | ENT_HTML401) . "</strong><br />\n"; }Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/PHPMailer/Exception.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.