> ## Knowledge Base Index
> Fetch the complete knowledge base index at: https://help.reach-book.com/sitemap.xml
> Use this file to discover available pages before exploring further.
> Pure-Markdown content can be obtained by appending a '.md' suffix to the content URLs listed in the sitemap (without the trailing slash).

# Customer database

1. [Help center](/)
2. [Integrations](/integrations)

# Customer database

Connect your own customer database so Reach-book.com can check whether a prospect is already a customer before you email them. Existing customers aren't sent follow-ups.

Open **Workspace settings → Customer database**. It has three tabs.

## Connection

* An HTTPS lookup URL
* GET or POST
* Authentication: none, bearer token, or an API key header
* A request template using `{{email}}` and `{{domain}}`

## Mapping

Tell Reach-book.com which part of your system's response means "this is a customer".

## Test

Click **Run a lookup** to try it with a real email.

Turn **Automatic checks** on to check new prospects automatically. Saving the connection runs earlier customer checks again. You can also check selected prospects with **Check customers** on the prospect list.