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

# What Is the Blocklist

The blocklist protects your customer database from invalid contacts. When customers sign up, subscribe, or place an order, they sometimes enter contacts that aren't real — typos, placeholder values, junk addresses, or test data. The blocklist gives you a single place to catch those entries before they pollute your database.

## What can go on the blocklist

The blocklist can hold any of these contact types:

* Email addresses
* Mobile phone numbers
* External customer identifiers
* Device identifiers
* Discount card numbers

## How contacts get on the blocklist

A contact can land on the blocklist in three ways:

1. **It's in the baseline list.** Maestra ships every new project with a pre-populated baseline of frequently mistyped or obviously invalid contacts. You can download this list and adjust it to fit your project.
2. **An administrator imports it.** You can upload a list of contacts to block at any time.
3. **It's added automatically.** If a contact exceeds the project's editing or merging limits, Maestra adds it to the blocklist and raises a warning on the project.

## How blocklist validation works

Blocklist checks run on imports and on contacts coming in through the API. They do **not** run when you add a contact manually through the interface — manual entry bypasses the blocklist on purpose, so support and ops can override it when they need to.

<Note>
  Adding a contact to the blocklist does **not** automatically remove it from existing customer profiles. The blocklist stops new bad data from being saved; it doesn't clean up data that's already there.
</Note>

## The blocklist doesn't stop campaigns

This is the most important thing to know: **adding a contact to the blocklist does not stop campaigns from being sent to it.** Blocklisted contacts stay reachable until you take an extra step.

To actually exclude a blocklisted contact from your campaigns, you need to either:

* Delete the customer from your database, or
* Clear the invalid contact value from the customer profile.

If you only add the contact to the blocklist, the customer profile keeps it and campaigns keep going out to it.

## When to use the blocklist

Use the blocklist to:

* Catch placeholder and test data (e.g., `test@test.com`, `noreply@example.com`, `+10000000000`) before it enters the database.
* Block known-bad addresses that keep showing up across signups.
* Auto-quarantine contacts that are being edited or merged too aggressively, which is a common sign of bot activity or broken integrations.

For ongoing list hygiene — suppressing unsubscribes, hard bounces, or spam complaints — use the standard subscription and deliverability tools. The blocklist is for invalid contacts, not for opted-out ones.