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Mails.ai

Email API for AI agents with per-inbound prompt-injection scoring, sender reputation and no cold email

freemiumFree $0/mo: 3,000 events/month, 1 agent, TypeScript SDK and REST, MCP server, magic-link signup with no card. Pro $20/mo: 50K sends and 50K inbound replies/month, 5 agents, HMAC-signed webhooks, injection scanning on every inbound. Scale $99/mo: 250K sends, 500K inbound, unlimited agents, per-agent allowlists and budgets, dedicated IP on request. A metered plan at $0.001/send, $0.002/inbound and $0.003/classify is listed as coming soon.View full pricing →

About Mails.ai

Mails.ai gives an AI agent its own real email address in a single API call — send, receive and reply — and is built around the assumption that the agent, not a human, is reading the inbox. Every inbound message arrives as a structured reply event carrying an injection score and a sender reputation figure, with intent and extracted entities available as an opt-in classification step, so an agent acts on typed fields rather than parsing a message body. A six-category prompt-injection scanner runs on every inbound and flags the event as quarantined above a 0.95 score, which is the security posture the whole product is organised around: an agent with an inbox is an agent with an untrusted input channel, and the platform treats it that way by default. Cold email is blocked at the API rather than in a terms-of-service clause, which is a deliberate deliverability decision — the reputation graph only works if the platform is not also carrying spam. Free sends come from a workspace subdomain with zero DNS setup; paid plans add custom domains verified with DNS records and per-domain DKIM signing. It ships a TypeScript SDK, REST API, HMAC-signed webhooks with an SDK reactor, per-agent allowlists and budgets, and an MCP server. The vendor states plainly that it has no sales team and no contact-us enterprise tier.

Key Features

Real inbox for an agent in one API call
Six-category prompt-injection scanner on every inbound
Structured reply events with injection score and sender reputation
Opt-in intent and entity classification
Cold email blocked at the API level
Custom domains with per-domain DKIM signing
TypeScript SDK, REST, HMAC webhooks and an MCP server

Tags

email-apiagentsprompt-injectionmcpdeliverability
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