Adjust applies the malformed advertising ID filter when device matching. It removes all invalid advertising IDs from your dataset. You don’t need to activate this filter; it is automatically on for all clients.

An advertising ID is a string containing a fixed number of characters. Each character in the string has a given range of permitted values. Advertising IDs always follow the same format, so if some characters are missing or appear where they shouldn’t, the ID is invalid and therefore fraudulent. This is true even if that device has other valid identifiers available.

## [View rejected traffic](view-rejected-traffic)

**Availability**

*   [Adjust’s Fraud Prevention Suite](/en/article/fraud-prevention-suite)
*   Enabled global rejection callbacks 

To view your rejected malformed advertising ID traffic, you must have the Fraud Prevention Suite enabled and global rejection callbacks set up. With these conditions met, you can view your rejected traffic as shown below.

### [In Deliverables and reports](in-deliverables-and-reports)

*   You can see a tracker called `untrusted devices::malformed advertising ID`

### [In your raw data](in-your-raw-data)

*   The `{activity_kind}` placeholder returns the value `rejected_install`
*   The`{rejection_reason}` placeholder returns `Malformed advertising id`


Malformed Advertising ID Filter

View rejected traffic

In Deliverables and reports

In your raw data