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

# Add Label

> Apply a Gmail label to one message.

The **Add Label** action applies an existing Gmail label to a message. Use it
to categorize processed mail, route inbox work, or mark a workflow stage.

## Inputs

| Input                   | Type           | Required | Description                            |
| ----------------------- | -------------- | -------- | -------------------------------------- |
| **Third-party account** | Google account | Yes      | Gmail account containing the message.  |
| **Message ID**          | String         | Yes      | Gmail ID of the message to update.     |
| **Label**               | String         | Yes      | Existing Gmail label name or label ID. |

Label names are matched after trimming whitespace and ignoring capitalization.
Supplying an exact Gmail label ID also works.

<Note>
  This action has no output. A successful run means Gmail accepted the label
  update.
</Note>

## Example

```text theme={null}
Gmail: Search Messages
  → Repeat over Message IDs
  → Gmail: Add Label ("Processed")
```

## Troubleshooting

<AccordionGroup>
  <Accordion title="Label not found">
    The action does not create labels. Create the label in Gmail first, then use
    its visible name or exact ID.
  </Accordion>
</AccordionGroup>