cx-newsletter/components/12-single_mail.php

<?php

namespace cx_newsletter;
use \Exception;

class single_mail {
    public string $title = '';
    public string $content = '';
    public array $headers = [];
    public bool $is_html = false;
    public ?string $to = null;
    public ?string $reply_to = null;

    public function is_good() : bool {
        return $this->validate() === null;
    }

    public function validate() : ?string {
        if ($this->reply_to === null) {
            return 'Reply to is not set in email.';
        }

        if ($this->to === null) {
            return 'Target email is not set.';
        }

        return null;
    }
}