Envelope – Open-source email API for AI agents (BYO email, MCP)
Human approval flows prevent agents from sending emails without review.
Free tier consolidates 6+ paid APIs into one key, but most tools already solve this.
AI agent developers building multi-tool integrations; LLM app builders needing standardized APIs.
LangChain Tool Hub · Anthropic MCP ecosystem · OpenAI Plugins
Human approval flows prevent agents from sending emails without review.
Free SMS and email verification for AI agent fleets at scale.
Another all-in-one workspace competing with Coda, Notion, and ClickUp.
First email API with native MCP support—Claude agents get 9 email tools instantly.
Own KumoMTA infrastructure beats reselling SES, but email-for-agents is getting crowded.
Dedicated inboxes per agent beat shared Gmail accounts for attribution and deliverability.