AGENT MAIL INFRASTRUCTURE

Give every agent a real inbox.

Durable, routable mailboxes with managed DNS, per-inbox DKIM, ReBAC policy and an append-only audit trail. Provision one in a single API call. It outlives the agent.

Start building See the console →

1 API call provisions a signed inbox in ~240ms, and 100% of delivery decisions are on the record.

SYSTEM / STATUS 09:14:02Z
Active inboxes
1,284
+37 last 24h
Throughput
3,142 /m
Provision p50
240ms
1 API call · signed inbox
Decisions audited
100%
delivered 98.7 · held 1.1 · rej 0.2
FLEETagents.northwind.email 6 OK 1 WARN 1 CRIT REFRESH 2s
Inbox Team Signing DNS Unread Rate
triage-q7k2m9@… support signed verified 12 428/m
support-tier1-a@… support signed verified 28 512/m
billing-resolver@… finance signed verified 03 140/m
sdr-outbound-3f@… growth degraded verified 00 077/m
recruiter-eu-2@… people signed pending 06 061/m
invoice-sync@… finance signed failed 44 000/m
TRUSTED TO ROUTE MAIL FOR AGENT FLEETS AT
NORTHWINDMeridian LabsBRIGHTWAVEColdgroveACME OPS
CAPABILITIES

Everything an agent inbox needs, behind one API.

Not a webmail clone — operational infrastructure. Provision and inspect fleets of inboxes, manage routing and DNS, configure authorization, and review every delivery decision.

MANAGED DNS & DKIM agents.northwind.email

Authoritative DNS projected straight from control-plane state. MX, SPF, DMARC, return-path and a per-inbox DKIM selector are published and rotated for you — no zone files, no copy-paste records.

Record State Last check
MX routed 2s
SPF aligned 2s
DMARC p=reject 2s
DKIM pbx-2026a 2s

  • Durable inboxes

    Lifecycle-managed mailboxes with threads, drafts, labels and events. Archive and reactivate without losing history.

  • Routing and addresses

    A permanent canonical address per inbox, plus reassignable aliases and custom delegated subdomains.

  • Authorization

    ReBAC underneath, product controls on top: access grants, communication policy, send-as and visibility.

  • Spam, not surprises

    Unknown senders land in a deliberate, warning-heavy surface. Reads require permission and are audited.

  • Events and audit

    Append-only logs for delivery, policy, auth and DNS. ReBAC-filtered streams deliver only what's authorized.

Explore the product →
INBOUND PIPELINE

Every message runs the same gauntlet.

The Email Record is written only after durable acceptance — never before. Authentication is not trust; trust is a policy decision, and every decision is logged.

append-only DMARC-aligned ReBAC-evaluated
DELIVERY PIPELINE5 STAGES
01
Authenticate
DMARC-style alignment. Auth ≠ trust.
PASS
02
Resolve route
Map address → live inbox + policy.
OK
03
Evaluate ReBAC
Trusted vs. unknown sender.
REVIEW
04
Decide
accept · spam · reject · block.
ACCEPT
05
Store record
Full RFC 5322, after acceptance only.
WRITTEN
ONE API · SELF-DESCRIBING

From zero to a signed inbox in one call.

A hosted HTTP API that describes itself at /llms.txt and /openapi.json — authenticated, audited, callable from any language. Typed SDKs and a hosted MCP endpoint are on the way.

HTTP Live now — Bearer-authenticated REST, resource-shaped, idempotent
SPEC Self-describing at /llms.txt & /openapi.json — point an agent straight at it
SDK Typed TypeScript & Python clients — coming soon
MCP Model Context Protocol tools — coming soon
Read the developer docs →
postillion.exec 
$ curl -X POST https://postillion.ai/v1/inboxes \
   -H "Authorization: Bearer sk_live_a1…7be" \
   -d '{ "name": "Triage", "team": "support" }'

→ inbox created · DKIM selector signed · zero tenant DNS
{
  "id": "ibx_a1f9",
  "canonical_address": "triage-q7k2m9@agents.northwind.email",
  "status": "active",
  "signing": { dkim: "ok", selector: "pbx-2026a" }
}
EVENTS & AUDIT

Every message, every decision — on the record.

Append-only records for lifecycle, policy, delivery, auth, and DNS. The event stream is ReBAC-filtered — only authorized events ever leave the building.

EVENTS.STREAM tail -f · RBAC-filtered policydeliveryauthdns
Accepted inbound from dana@brightwave.io · DMARC aligneddelivery2m
Routed to spam: noreply@unknown-sndr.co — SPF faildelivery6m
⚙Communication control added: allow domain meridian-labs.compolicy14m
◉Spam content read by key sk_live_a1…7be (audited)content33m
Authentication failure: m.vale@oldgrove.net — DKIM signature invalidauth1h
Authenticate, then trust
DMARC alignment required for an authenticated author. Authentication alone never grants delivery.
ReBAC, hidden
OpenFGA decides every relationship — users see product controls, never tuples or model IDs.
Platform safety wins
No customer grant can override a platform abuse, security, or deliverability block.
Read the security model →
READY ON THE FREE TIER

Give your agents an inbox that outlives them.

Spin up your first durable, routable inbox in minutes — no credit card, no DNS setup. Just an API key and three calls.

Get your API key Browse the docs
$ curl https://postillion.ai/llms.txt  ·  curl https://postillion.ai/openapi.json