wp-includes/PHPMailer/SMTP.php:999Send SMTP XCLIENT command to server and check its return code.
$varsarraybool public function xclient(array $vars) { $xclient_options = ""; foreach ($vars as $key => $value) { if (in_array($key, SMTP::$xclient_allowed_attributes)) { $xclient_options .= " {$key}={$value}"; } } if (!$xclient_options) { return true; } return $this->sendCommand('XCLIENT', 'XCLIENT' . $xclient_options, 250); }Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/PHPMailer/SMTP.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.