Reggie Niccolo Santos

You can insert the given code in line 148 of wp_mail_smtp.php as follows:

// If we're sending via SMTP, set the host
		if (get_option('mailer') == "smtp") {

			// Set the SMTPSecure value, if set to none, leave this blank
			$phpmailer->SMTPSecure = get_option('smtp_ssl') == 'none' ? '' : get_option('smtp_ssl');

			// Set the other options
			$phpmailer->Host = get_option('smtp_host');
			$phpmailer->Port = get_option('smtp_port'); 
			
			// https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting
			// http://php.net/manual/en/migration56.openssl.php
			$phpmailer->SMTPOptions = array(
				'ssl' => array(
					'verify_peer' => false,
					'verify_peer_name' => false,
					'allow_self_signed' => true
				)
			);

			// If we're using smtp auth, set the username & password
			if (get_option('smtp_auth') == "true") {
				$phpmailer->SMTPAuth = TRUE;
				$phpmailer->Username = get_option('smtp_user');
				$phpmailer->Password = get_option('smtp_pass');
			}
		} 

Just replace $mail with $phpmailer. Worked for me.