# MailboxKit

> Email infrastructure for AI agents. Give any AI agent a real email address in 30 seconds. One API call to send. Webhooks to receive. Built for autonomous agents that need to communicate over email.

MailboxKit provides a REST API that lets AI agents send, receive, and reply to emails programmatically. Each agent gets a unique email address (e.g. agent-42@agent.mailboxkit.com) or can use a custom domain. Inbound emails are delivered in real time via webhooks. Conversation threading is automatic via References and In-Reply-To headers.

Key facts:
- API Base URL: https://mailboxkit.com/api/v1
- Authentication: Bearer token (API key)
- Pricing: $0.002 per email, $0.001 per attachment, pay-as-you-go
- Free credit: $1.00 (500 emails) on signup
- No subscriptions or monthly minimums
- Custom domains with automated DKIM, SPF, and DMARC verification
- Email open and click tracking
- Attachment support via signed URLs

## Docs

- [Agent Skill File](https://mailboxkit.com/skill.md): Machine-readable guide for AI agents — self-register, send, receive, and reply to emails via API
- [API Documentation](https://mailboxkit.com/api-docs): Complete REST API reference — endpoints for inboxes, messages, threads, webhooks, domains, and API keys
- [Getting Started](https://mailboxkit.com/register): Self-register via API or sign up for the dashboard — get an agent email address in one request
- [Pricing](https://mailboxkit.com/pricing): Pay-as-you-go pricing details and top-up options
- [Enterprise](https://mailboxkit.com/enterprise): Volume pricing, dedicated IPs, SLA, and white-label options

## Use Cases

- [Email for AI Coding Agents](https://mailboxkit.com/use-cases/coding-agents): Let coding agents (Claude Code, Codex, etc.) send status updates, receive code review feedback, and collaborate with teams over email
- [Email for AI Customer Support Agents](https://mailboxkit.com/use-cases/customer-support): Receive support tickets, auto-generate responses, maintain conversation context, and escalate to humans
- [Email for AI Sales & Outreach Agents](https://mailboxkit.com/use-cases/sales-outreach): Personalized outreach at scale, automated follow-ups, open tracking, and reply detection
- [Email for AI Research Agents](https://mailboxkit.com/use-cases/research-agents): Send information requests, collect responses, manage multi-party correspondence, and summarize threads
- [Email for AI Executive Assistants](https://mailboxkit.com/use-cases/executive-assistants): Schedule meetings, handle routine correspondence, draft replies, and manage inbox triage

## Blog

- [Why AI Agents Need Email](https://mailboxkit.com/blog/why-ai-agents-need-email): The case for giving AI agents real email addresses
- [Give Claude Code Email in 60 Seconds](https://mailboxkit.com/blog/give-claude-code-email-in-60-seconds): Step-by-step tutorial for adding email to Claude Code via SKILL.md
- [Best Email APIs for AI Agents 2026](https://mailboxkit.com/blog/best-email-apis-for-ai-agents-2026): Comparison guide of email APIs built for AI agent workflows

## Optional

- [Privacy Policy](https://mailboxkit.com/legal/privacy)
- [Terms of Service](https://mailboxkit.com/legal/terms)