SMTP::getServerExt( string $name ): string|bool|null

1298    public function getServerExt($name)1299    {1300        if (!$this->server_caps) {1301            $this->setError('No HELO/EHLO was sent');1302 1303            return null;1304        }1305 1306        if (!array_key_exists($name, $this->server_caps)) {1307            if ('HELO' === $name) {1308                return $this->server_caps['EHLO'];1309            }1310            if ('EHLO' === $name || array_key_exists('EHLO', $this->server_caps)) {1311                return false;1312            }1313            $this->setError('HELO handshake was used; No information about server extensions available');1314 1315            return null;1316        }1317 1318        return $this->server_caps[$name];1319    }