Outbound Mail Agent

Overview

Layer 4 Act on the Mental Model. Outbound Mail runs after inbound accepts clean contact mail: parallel Processing Q and Thank-you Q workers (no SES send on inbound).

Behavior

• Parallelization (Anthropic). Inbound enqueues Processing Q and Thank-you Q together; the two paths run independently. See Building effective agents.
• Independent outcomes. Process (today: forward) and thank-you do not wait on each other. Each records its own DynamoDB fields (forward_ses_id, thank_you_ses_id / thank_you_status).
• Per-queue idempotency. Retries skip work already done on that queue so hotmail is not double-forwarded and the sender is not double-thanked.
• Hard send failures retry. SES or unexpected errors raise so that queue redelivers (up to 3 receives), then that queue’s DLQ. Soft thank-you compose failures still attempt a template send.
• Shared raw MIME. Both workers reload ses-raw/<messageId> from S3; they do not depend on the inbound Lambda staying warm.

Send flow

Inbound fans out to both queues (Parallelization); either path can finish first. Diagram key: ✦ AI agent · second line = Anthropic workflow · purple = actor · white = service.

---
config:
  theme: default
  themeVariables:
    background: "#ffffff"
    fontSize: "14px"
---
flowchart TB
    inbound["✦ Inbound Mail agent
Routing"]
    procQ[Processing Q]
    thanksQ[Thank-you Q]
    procAgent["Processing worker
SES forward"]
    thanksAgent["✦ Thank-you Mail
Parallelization"]
    actionNode["SES forward
FORWARD_TO"]
    composeNode["✦ Compose thank-you
Parallelization"]
    thanksNode["SES thank-you
to sender"]
    procDone[Process recorded]
    thanksDone[Thank-you recorded]
    procDlq["Processing DLQ
after 3 receives"]
    thanksDlq["Thank-you DLQ
after 3 receives"]
    alarm[CloudWatch alarm]

    inbound --> procQ
    inbound --> thanksQ
    procQ --> procAgent --> actionNode --> procDone
    thanksQ --> thanksAgent --> composeNode --> thanksNode --> thanksDone
    procAgent -->|hard failure| procQ
    procQ -->|max receives| procDlq --> alarm
    thanksAgent -->|hard SES failure| thanksQ
    thanksQ -->|max receives| thanksDlq --> alarm

    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 inbound,thanksAgent,composeNode agent
    class procQ,thanksQ,procAgent,actionNode,thanksNode,procDone,thanksDone,procDlq,thanksDlq,alarm service