# Add to list

Adds the value of a field to an account [list](/en/rules/lists/), optionally with an expiration.

| Configuration       | Content                                                            |
| :------------------ | :------------------------------------------------------------------ |
| List                | list existing in the account                                        |
| Source: Value       | text or integer field whose value will be added                     |
| Setting: Expires in | `30m`, `12h`, `1d`; minimum `5m`, maximum 2 years; blank = permanent |

It lets a rule incorporate what it has already observed. A condition detects the behavior and writes to the list, and the following events check that list with an ordinary condition:

```
Event 1, condition:  "email_velocity" in %bot.triggered_cells
         action:     Add to list → $user_email to @blocked_emails, expires in 1d

Event 2, condition:  $user_email in @blocked_emails
         action:     Set field → blocked = "true"
```

With an expiration, recovery becomes an explicit policy: the entry leaves the list when it expires, instead of depending on the window of the analysis that originated it.

Points to consider:

- **A repeat does not duplicate**: adding a value already on the list only renews its expiration.
- **Invalid values are ignored**: a blank value, or one outside the format the list accepts, is not added and does not interrupt processing.
- **Removal is periodic**: expired entries are removed by sweeps every few minutes, so an entry may keep counting a little past its expiration; that is why the minimum expiration is 5 minutes.
- **Full lists stop growing**: once the item limit is reached, new values stop being added, but existing ones keep being renewed. See [limits and parameters](/en/limits/#rules-and-lists).
- **The simulator does not write to the list**: because it changes data outside the event, this action is skipped during a simulation.