Inbound Mail Agent

Overview

Layer 2 Decide on the Mental Model. One Inbound Mail agent in the SES receipt Lambda (opglabs-prod-inbound-api). A second Lambda (mail-events) only logs bounce and complaint notifications.

Behavior

• Verdict-gated disposition. Virus FAIL drops immediately; spam FAIL quarantines and stops; only clean mail is stored under inbound/ and handed off.
• No SES send on inbound. Sends run on Outbound Mail (Processing Q and Thank-you Q) so send retries cannot re-run categorize or double-claim inbound work.
• Routing (Anthropic). Clean mail is ranked by a low-cost LLM call — OpenAI gpt-4o-mini or Typesafe Jev — into an allowlisted category slug (or general). See Building effective agents.
• Parallelization (Anthropic). After rank, inbound enqueues Processing Q and Thank-you Q together (action=queued).
• Spam-scanned, still untrusted. Email body is wrapped as untrusted data after SES scan. The model evaluates request intent only.
• Idempotent claim. DynamoDB keyed by message id: terminal actions include queued, forwarded, quarantined, dropped, skipped.
• Retry then dead letter queue. A failed inbound async invoke is retried by Lambda (up to 2 times), then the inbound SQS DLQ. Each outbound queue has its own DLQ.
• Delivery events separate from processing. Bounce and complaint come via SNS into mail-events.

Receipt flow

Clean mail is categorized (Routing), then fans out to both outbound queues (Parallelization); spam quarantines; virus drops. Diagram key: ✦ AI agent · second line = Anthropic workflow · purple = actor · white = service.

---
config:
  theme: default
  themeVariables:
    background: "#ffffff"
    fontSize: "14px"
---
flowchart TB
    person[Person]
    ses[SES plus S3 raw]
    agentNode["✦ Inbound Mail agent
Routing"]
    rejectNode["Drop virus or
quarantine spam"]
    skipNode["Already done
skip resend"]
    systemOne["✦ System 1 categorize
Routing"]
    labelNode["Category label
e.g. project_inquiry"]
    queuedNode["action queued
Parallelization"]
    procQ[Processing Q]
    thanksQ[Thank-you Q]
    outbound["✦ Outbound Mail
Parallelization"]
    mailEvents["mail-events
bounce and complaint"]
    retry[Lambda retry]
    dlq[Inbound DLQ]
    alarm[CloudWatch alarm]
    itSupport[IT Support]

    person --> ses --> agentNode
    ses -.-> mailEvents
    agentNode -->|virus or spam FAIL| rejectNode
    agentNode -->|already done| skipNode
    agentNode -->|clean| systemOne
    systemOne -->|top ranked label| labelNode
    labelNode --> queuedNode
    queuedNode --> procQ
    queuedNode --> thanksQ
    procQ --> outbound
    thanksQ --> outbound
    agentNode -->|error| retry
    retry -->|retries exhausted| dlq
    dlq --> alarm --> itSupport

    classDef agent fill:#e8f0ee,stroke:#0f3d36,stroke-width:2px,color:#0d0d0d
    classDef service fill:#fafaf8,stroke:#c8c8c2,stroke-width:1px,color:#0d0d0d
    classDef actor fill:#f3eef8,stroke:#6b4f9a,stroke-width:2px,color:#0d0d0d
    class agentNode,systemOne,outbound agent
    class ses,rejectNode,skipNode,labelNode,queuedNode,procQ,thanksQ,mailEvents,retry,dlq,alarm service
    class person,itSupport actor