MailGuard: Cold Email Spam-Trigger, Deliverability & Live MX/DMARC Scorer Chrome Extension (MV3 + 180 SpamAssassin Rules CSV)

Replace $29–$49/mo email coach extensions (like Lavender Pro) with a 100% local Manifest V3 Chrome Extension + Full Unminified Source Code. MailGuard scores your B2B cold emails and newsletters in real time against 180+ SpamAssassin, Mimecast, Proofpoint, and Gmail Promotions tab trigger patterns, calculates word-count and link-density penalties, and queries Cloudflare DNS-over-HTTPS (DoH) to inspect your recipient domain's live MX gateway and _dmarc policy before you hit send.