Skill

multimail

Email-as-a-Service for AI agents. Inbound email converted to markdown, outbound markdown converted to HTML. Built on...

Verified: 2026-05-13 (printing-press-ingest-2026-05-13+enrich-capability-skill)

When to use multimail

Choose if

You're building an agent that needs to send and receive real email — with markdown in and HTML out — and want first-class oversight workflows (pending-approval queue + approve/reject) plus typed audit logs. Alternative class is Resend / Postmark / SendGrid wrapped by a generic SMTP MCP; pick Multimail when the agent itself needs the inbox (inbound parsing to markdown) and not just outbound transactional sends.

Avoid if

You only need outbound transactional email at scale and don't care about inbound parsing — a dedicated transactional ESP (Resend, Postmark) will have higher deliverability and richer analytics. Also avoid for free-tier workloads that require custom domains, which Multimail gates to Pro/Scale.

Risk Flags

  • HIGH data_quality `account delete` hard-deletes all tenant data. API keys are returned only once at creation — no recovery mechanism. Atomic persistence required on first response.
  • MEDIUM rate_limit Several endpoints have low IP-bound caps: resend-confirmation 1/10min; funnel-tracking 30/min/IP; multimail-export 1/hour; well-known lookup 10/IP/hour. Proof-of-work challenges expire in 5 minutes.
  • MEDIUM scope Capabilities are scope-gated: `read`, `send`, `admin`, `oversight`. An agent without the right scope will see exit-code-4 auth failures rather than partial functionality.
  • LOW scope Custom domains require Pro/Scale tier on the Multimail side. Free-tier agents will be confined to the platform-managed sender domain.

Cost

Type: Freemium · Free tier: The CLI binary is free to install. Multimail itself runs a freemium plan where the free tier supports the core inbound-markdown / outbound-HTML flow; paid tiers unlock custom domains and higher quotas.

Hidden costs

  • Custom domains are Pro/Scale-only; the README references "Plan upgrade" and Stripe checkout but does not publish tier prices. Free plan covers the documented API surface for sandbox-class agents.

Install

Default

npx -y @mvanhorn/printing-press install multimail
# Configure Multimail API key (scopes: read | send | admin | oversight):
export MULTIMAIL_API_KEY=<your-key>

Setup docs →

Estimated time to first success: ~10 min

Dependencies

Minimum runtime: Node.js 18+ (via npx) — pre-built macOS/Unix binaries available

Distribution

Repository
https://github.com/mvanhorn/printing-press-library
License
MIT