email

Email worker for the iii engine. SMTP send + real-time IMAP read with IDLE push. The worker refuses to fall back to polling: an IMAP server without IDLE fails fast at startup with E610. Inbound messages flow through the email::new-mail trigger type, fanned out the moment the server pushes EXISTS.

Credentials live in harness/auth-credentials under provider key email::. Pair both workers in any real deployment.

Install

iii worker add harness/auth-credentials
iii worker add email

Quickstart

use iii_sdk::{register_worker, InitOptions, protocol::TriggerRequest};
use serde_json::json;

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    let worker = register_worker("ws://localhost:49134", InitOptions::default());
    let result = worker.trigger(TriggerRequest {
        function_id: "email::send".into(),
        payload: json!({
            "account": "support",
            "to": ["recipient@example.com"],
            "subject": "Your ticket has been updated",
            "text": "Hi — thanks for reaching out."
        }),
        action: None,
        timeout_ms: Some(30_000),
    }).await?;
    println!("{result:#?}");
    Ok(())
}

import { registerWorker } from 'iii-sdk'

const worker = registerWorker('ws://localhost:49134')
await worker.trigger({
  function_id: 'email::send',
  payload: {
    account: 'support',
    to: ['recipient@example.com'],
    subject: 'Your ticket has been updated',
    text: 'Hi — thanks for reaching out.',
  },
})

from iii import register_worker

worker = register_worker("ws://localhost:49134")
worker.trigger({
    "function_id": "email::send",
    "payload": {
        "account": "support",
        "to": ["recipient@example.com"],
        "subject": "Your ticket has been updated",
        "text": "Hi — thanks for reaching out.",
    },
})

Other entry points: email::accounts::list, email::list, email::get, email::search, email::flag, email::move, email::attachment::get.

Configuration

accounts:
  # Send-only: only smtp:, provider: smtp.
  support:
    provider: smtp
    from: "Support <support@example.com>"
    smtp:
      host: smtp.example.com
      port: 587
      starttls: true

  # Two-way: smtp: + imap:, provider: imap.
  inbox:
    provider: imap
    from: "Inbox <inbox@example.com>"
    smtp:
      host: smtp.example.com
      port: 587
      starttls: true
    imap:
      host: imap.example.com
      port: 993
      tls: true
      folders: ["INBOX"]

limits:
  max_attachment_bytes: 26214400        # 25 MiB
  max_recipients: 100                   # to + cc + bcc combined
  send_timeout_ms: 30000
  imap_connect_timeout_ms: 15000

Credentials are fetched on every connect from harness/auth-credentials under provider key email:: with shape { "type": "api_key", "username": "...", "password": "..." }. For Gmail, generate an app password at https://myaccount.google.com/apppasswords — the worker accepts both spaced (abcd efgh ijkl mnop) and joined (abcdefghijklmnop) formats.

Triggers

Subscriber config:

triggers:
  - type: email::new-mail
    function_id: my-worker::on-mail
    config:
      account: support
      folder: INBOX                # optional, default "INBOX"
      handler_timeout_ms: 30000    # optional, default 30000

Payload your function receives per inbound message:

{
  "account":    "support",
  "folder":     "INBOX",
  "uid":        12345,
  "message_id": "<abc@mx.example.com>",
  "from":       "sender@example.com",
  "subject":    "Ticket #42",
  "snippet":    "first ~200 chars of body",
  "ts":         "2026-05-28T10:14:00+00:00"
}

The dispatch is event-driven off the server's EXISTS push — within milliseconds of a new message landing in the watched folder.

Local development & testing

# In one terminal: start the engine
iii

# In another: build & run the worker
cargo run --release -- --url ws://127.0.0.1:49134 --config ./config.yaml

The worker registers 8 functions + 1 trigger type, then spawns one persistent IMAP+IDLE supervisor per (account, folder) configured with provider: imap. Reads (list/get/search/flag/move/attachment::get) borrow an on-demand session from a separate pool so the half-duplex IMAP socket is never shared with the supervisor.

Seed credentials before exercising email::send or any IMAP function:

iii trigger auth::set_token \
  provider=email::support \
  credential='{"type":"api_key","username":"you@example.com","password":"<app-password>"}'

--manifest prints the registry-publish JSON without touching the engine:

cargo run -- --manifest | jq .

Tests

cargo test                       # unit tests (config, manifest, triggers)
cargo test --test bdd            # cucumber: --manifest subprocess contract

tests/bdd.rs self-skips @engine scenarios when no engine is reachable on III_ENGINE_WS_URL (default ws://127.0.0.1:49134), so contributor laptops without a running engine still pass @pure scenarios.

Verification before publishing

The full preflight checklist for binary workers (workers/binary-worker.md):

cargo fmt --all -- --check
cargo clippy --all-targets --all-features -- -D warnings
cargo test --all-features
./target/debug/email --manifest | jq .

Errors