Mail Security Tools API: Prepaid email setup watch: up to 25 domains for 30 days, webhook on change. Pay once, then each domain's SPF, DMARC, DKIM (common selectors), MX and score are re-checked about once a day for 30 days. When something changes or breaks you get an HMAC-signed JSON POST at your https webhook_url (event watch.changed, kind changed|broke, before/after). A watch.created POST is se