Design of record for OpenMail — one Go binary (smtpd/core/sender/mcp) + Postgres
+ object storage on a VPS. Covers inbound SMTP/MIME/threading, outbound
deliverability (relay-default, self-host opt-in), data model, AgentMail-shaped
v0 API + MCP server, and an MVP milestone path.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>