wp-includes/PHPMailer/SMTP.php:870Send an SMTP HELO or EHLO command.
$hoststringoptional''bool public function hello($host = '') { //Try extended hello first (RFC 2821) if ($this->sendHello('EHLO', $host)) { return true; } //Some servers shut down the SMTP service here (RFC 5321) if (substr($this->helo_rply, 0, 3) == '421') { return false; } return $this->sendHello('HELO', $host); }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.