> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sentfrom.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# FAQ & troubleshooting

> Common questions and how to resolve the errors you might hit.

## Getting started

<AccordionGroup>
  <Accordion title="How do I get an API key?">
    In the [dashboard](https://console.sentfrom.ai) → **API keys** → create a key. It looks like
    `sf_live_…`. Pass it as `Authorization: Bearer sf_live_…` on every request. Keys are
    workspace-scoped; create one per service or environment and revoke freely.
  </Accordion>

  <Accordion title="How do I create my first inbox?">
    `POST /inboxes { "local_part": "support-bot" }` returns an address on the shared
    `mail.sentfrom.ai` domain, live immediately — no DNS setup. See [Inboxes](/concepts/inboxes).
  </Accordion>

  <Accordion title="How do I handle inbound email?">
    Two options: register a [webhook](/concepts/receiving) for `message.received` (push,
    recommended), or poll `GET /messages?inbox_id=…`. For low-latency agents, stream events over
    the [realtime WebSocket](/guides/realtime).
  </Accordion>

  <Accordion title="How do I keep replies in the same conversation?">
    Use `POST /messages/{id}/reply` — SentFromAI derives the recipient and sets the
    `In-Reply-To`/`References` headers automatically. See [Threads](/concepts/threads).
  </Accordion>

  <Accordion title="How do I block or allow specific senders?">
    Add rules with `POST /lists` (`kind`: allow/block, `direction`, `pattern`). See
    [Allow & block lists](/guides/allow-block-lists). Bounces and complaints are auto-suppressed
    separately.
  </Accordion>
</AccordionGroup>

## Errors

<AccordionGroup>
  <Accordion title="What does a 401 mean?">
    Missing or invalid API key. Check the `Authorization: Bearer …` header and that the key
    hasn't been revoked.
  </Accordion>

  <Accordion title="What does a 402 (with upgrade: true) mean?">
    A plan limit was hit. The `error` tells you which: `inbox_limit_reached`,
    `custom_domains_require_paid_plan`, `dedicated_subdomain_requires_scale`, or
    `storage_limit_reached`. Upgrade from [Billing](https://console.sentfrom.ai).
  </Accordion>

  <Accordion title="Why do I get 409 &#x22;address_taken&#x22;?">
    That inbox address is already in use (addresses are globally unique on the shared domain).
    Pick a different `local_part`.
  </Accordion>

  <Accordion title="Why do I get 413 &#x22;attachment_too_large&#x22;?">
    A single email's attachments must fit within \~7 MB (the encoded message stays under the 10 MB
    provider limit). Split large files or share a link instead. See [Attachments](/guides/attachments).
  </Accordion>

  <Accordion title="Why do I get 422 on send?">
    Every recipient was suppressed (a prior bounce/complaint) or on your block list, so there was
    no one deliverable. The response lists the blocked addresses.
  </Accordion>
</AccordionGroup>

## Deliverability

<AccordionGroup>
  <Accordion title="Why are my emails bouncing?">
    Hard bounces add the address to your automatic suppression list so you don't keep sending to
    it. Check the recipient is valid; subsequent sends to a suppressed address are dropped.
  </Accordion>

  <Accordion title="Why isn't my custom domain verifying?">
    Publish all returned DNS records (DKIM, SPF, DMARC, MAIL-FROM) exactly, with no extra quoting,
    and give DNS a few minutes to propagate. See the [DNS guides](/guides/dns/cloudflare) and
    [Deliverability](/guides/deliverability).
  </Accordion>

  <Accordion title="How do I prevent duplicate sends?">
    Pass a unique `client_id` on `POST /messages`. A repeated `client_id` returns the original
    message instead of sending again — safe to retry after a timeout.
  </Accordion>

  <Accordion title="Why are my emails going to spam?">
    Authenticate with a verified custom domain (SPF/DKIM/DMARC), warm up volume gradually, and keep
    bounce/complaint rates low. Full guidance in [Deliverability](/guides/deliverability).
  </Accordion>
</AccordionGroup>