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

# Opt-in & auto-reply

> Let people who opted out re-subscribe by text, and send an automatic confirmation.

## Overview

[Opt-in](/getting-started/glossary#opt-in) is how a contact who previously opted out
can **re-subscribe** to your messages. When someone replies with an opt-in keyword
like **START**, Autocampaign AI clears their opt-out flag, records the consent on their
timeline, and can send an optional welcome-back confirmation.

You set up opt-in keywords and the auto-reply at **Settings → Opt-out**, in the
right-hand **Opt-In Settings** column (next to [Opt-out](/compliance/opt-out)).

<Info>
  **Time to complete:** \~5 minutes  ·  **Difficulty:** Beginner  · 
  **Who can do this:** anyone with access to Settings can view; you need to be an
  Owner or Admin to make changes.
</Info>

## How opt-in works

<Steps>
  <Step title="A contact replies with an opt-in keyword">
    Autocampaign AI checks incoming messages for opt-in keywords. Detection works the
    same as opt-out. Capitals don't matter, and the keyword must be at the start of
    the message as a whole word (`STARTUP` won't match `START`).
  </Step>

  <Step title="The contact is re-subscribed">
    If the contact was previously opted out, Autocampaign AI clears the flag and records an
    **Opted in** event on their timeline. They can receive campaigns again. If they
    were never opted out, nothing changes.
  </Step>

  <Step title="An optional confirmation is sent">
    If you've set an opt-in auto-reply, Autocampaign AI sends it. See the exceptions for
    keywords your provider answers itself, below.
  </Step>
</Steps>

### The default keywords

Every workspace starts with the carrier-standard opt-in keywords:

```
START, UNSTOP, YES
```

<Note>
  Opt-in only affects contacts who are **currently opted out**. An opt-in keyword
  from an unknown number (one that has never contacted you) is ignored. It does
  not create a contact.
</Note>

## Set up opt-in

<Steps>
  <Step title="Open opt-in settings">
    Go to **Settings → Opt-out** and use the **Opt-In Settings** column on the right.
  </Step>

  <Step title="Manage keywords">
    Add your own re-subscribe keywords (for example, `subscribe`) under **Keywords**.
    Up to **75** per workspace, same rules as opt-out.
  </Step>

  <Step title="Set a welcome-back auto-reply (optional)">
    Under **Auto-Reply Message**, enter an optional confirmation (up to **1,600
    characters**) sent when a contact re-subscribes, then **Save**.
  </Step>
</Steps>

## Auto-replies are not written by AI

The opt-in and opt-out auto-replies are **fixed messages you write yourself**. The
exact text you enter is sent back word for word. They are **not** AI-generated.

If you want AI to answer, qualify, or route **incoming conversations**, that's a
separate feature. See [AI Employees](/automation/ai-employees), which work alongside
your [Inbox](/inbox/overview). Compliance replies (opt-in/opt-out confirmations)
always send your exact text, on purpose.

## Keywords your provider answers for you

Like opt-out, your [provider](/getting-started/glossary#provider) (the phone company
behind your numbers) reserves the standard opt-in keywords:

* **Twilio** automatically handles `START, UNSTOP, YES` and sends its own
  confirmation, so Autocampaign AI skips its reply for those. Your custom keywords are
  answered by Autocampaign AI.
* **Telnyx** behaves the same way when advanced opt-in sync is turned on for the profile.

## How consent is recorded

Autocampaign AI records how each contact entered your list as a **consent source**.
Examples: CSV import, manual entry, web form ([join link](/campaigns/join-links)),
text link, inbound SMS, or an ad platform (Google/Meta). Join-link web forms also store
a snapshot of the exact consent wording, timestamp, and other evidence per
submission. Opt-in and opt-out events are logged on the contact's activity
timeline so you have a record if anyone asks.

## FAQ

<AccordionGroup>
  <Accordion title="Does replying START always re-subscribe someone?">
    Only if they were opted out. If they were never opted out, nothing happens:
    no change and no reply.
  </Accordion>

  <Accordion title="Will an opt-in from a brand-new number create a contact?">
    No. Opt-out is different: a STOP is recorded even from unknown numbers, for
    compliance. An opt-in from a number that never contacted you is ignored.
  </Accordion>

  <Accordion title="Is the opt-in confirmation written by AI?">
    No. It's the fixed message you write yourself. For AI-assisted replies to
    incoming messages, use an [AI Employee](/automation/ai-employees).
  </Accordion>

  <Accordion title="Why didn't my welcome-back message send?">
    For the standard keywords (START, UNSTOP, YES) the carrier sends its own
    reply and blocks Autocampaign AI's. Custom keywords you add are answered by Autocampaign AI.
  </Accordion>
</AccordionGroup>

## Troubleshooting

<AccordionGroup>
  <Accordion title="Why isn't a re-subscribed contact getting campaigns?">
    Confirm an **Opted in** event appears on their timeline. If they opted in after
    a campaign's audience was built, they'll be included in the next send.
  </Accordion>

  <Accordion title="Why isn't my custom opt-in keyword working?">
    Check it's spelled correctly and that the incoming message *starts* with it.
    The keyword must be at the start of the message and be a whole word.
  </Accordion>
</AccordionGroup>

<Card title="Opt-out management" icon="ban" href="/compliance/opt-out">
  STOP handling and keyword settings.
</Card>