global-autoresponder/exec/lib/MailSender.php

<?php
declare(strict_types=1);

final class MailSender
{
    public static function buildMessage(string $from, string $to, string $subject, string $body): string
    {
        foreach ([$from, $to, $subject] as $value) {
            if (str_contains($value, "\r") || str_contains($value, "\n")) {
                throw new InvalidArgumentException('Invalid subject or address header');
            }
        }
        $encodedSubject = '=?UTF-8?B?' . base64_encode($subject) . '?=';
        $headers = [
            'From: ' . $from,
            'To: ' . $to,
            'Subject: ' . $encodedSubject,
            'Auto-Submitted: auto-replied',
            'Content-Type: text/plain; charset=UTF-8',
            'Content-Transfer-Encoding: 8bit',
        ];
        return implode("\n", $headers) . "\n\n" . str_replace(["\r\n", "\r"], "\n", $body) . "\n";
    }

    public function send(string $sendmail, string $from, string $to, string $subject, string $body): bool
    {
        $message = self::buildMessage($from, $to, $subject, $body);
        if (!is_file($sendmail) || !is_executable($sendmail)) {
            return false;
        }
        $process = proc_open([$sendmail, '-t', '-i'], [['pipe', 'r'], ['pipe', 'w'], ['pipe', 'w']], $pipes);
        if (!is_resource($process)) {
            return false;
        }
        fwrite($pipes[0], $message);
        fclose($pipes[0]);
        stream_get_contents($pipes[1]);
        stream_get_contents($pipes[2]);
        fclose($pipes[1]);
        fclose($pipes[2]);
        return proc_close($process) === 0;
    }
}