We were building an agent system and wanted email as a trigger. We decided to take it out and made it a standalone service.

The primary email features we wanted and used for our own agent system:

1. Email threading stays consistent with agent conversation threading

2. Human in the loop review for outbound emails (especially during testing phase)

3. Quick onboarding/offboarding email addresses for agents within minutes

4. Websocket for local agents and at-least-once webhook delivery for Cloud agents

Not yet: DMARC (only SPF/DKIM today), scoped API keys, HA/multi-region (single VM + single Postgres), app-layer email data encryption, compliance attestations (SOC 2/HIPAA).

GitHub: https://github.com/Mnexa-AI/e2a

Hosted: https://e2a.dev/

Appreciate any feedback / contributions.

There is also this project for using email as a coordination layer between agents for multi-agent workflow.

https://github.com/Dicklesworthstone/mcp_agent_mail

Similar open-source project https://github.com/DataCovey/nornweave

Inbox-as-a-Service for AI Agents Open-source, self-hosted API that turns standard email providers into intelligent, stateful email for LLMs via REST or MCP.