A quick reference against the crowded deliverability tools market.
- Free forever on the core. Not a trial. Not a lead magnet. Unlimited placement tests, no credit card.
- 4,000+ real seed mailboxes. 40x what most competitors disclose. Real accounts on real providers.
- 30+ providers. Gmail, Outlook family, Yahoo, Mail.ru, Yandex, Rambler, ProtonMail, iCloud, GMX, Web.de, Zoho, T-Online, 1&1, and more. Long-tail coverage the others skip.
- MCP server. Agent-native tool use. Claude Desktop, Claude Code, Cursor, Zed, custom MCP clients.
- A2A ready. Agent-to-agent orchestration with task-graph delegation.
- Gmail folder detection. Primary / Promotions / Updates / Social / Spam — not just Inbox / Spam.
- Post-send tracking. Reclassifications detected for up to 72h; alerts on folder flips.
- Presend analyzer. Stop-words + AI human-perception + link intelligence, before you hit send.
- Free domain monitoring. SPF/DKIM/DMARC/PTR/MX/blacklist — daily, alerts free.
- 100K+ tests/day on the free tier. Rolling 24h windows, not calendar-day resets. No signup required to start.
Line them up against any competitor
Price, seeds, providers, agent support, folder detection, post-send, presend, monitoring, signup friction, capacity. Take the list into any evaluation. Try Inbox Check.
FAQ
Which of these is the biggest moat?
Seed network + agent protocol support. Both are compounding, both are hard to reproduce, and neither is on a competitor roadmap publicly.
What's missing that competitors have?
Some competitors have nicer-looking dashboards. We prioritise accuracy and completeness over visual polish; PRs welcome if you want to redesign ours.
Is there a feature you won't build?
A warmup pool. For reasons laid out in our manifesto.
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