> For the complete documentation index, see [llms.txt](https://docs.emaillabs.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.emaillabs.io/en/email/sender-security/senders-authorization/how-the-sandbox-domain-works.md).

# How the Sandbox Domain Works

The sandbox domain is a solution that allows new customers to immediately start sending emails via API and SMTP following successful account verification. This mechanism enables integration testing right after access is activated by the Customer Support Team, removing the barrier of having to configure DNS records straight away.

To send your first message, you need to generate a sender address (From) assigned to the provided test domain.

### **Instructions for creating a sender address for the sandbox domain**

1. Go to the **E-mail addresses authorization** tab and click the **+ New sender's address** button.
2. In the window that appears, enter your preferred address prefix (the text before the @ sign).
3. From the dropdown list on the right, select the name of your assigned sandbox domain.
4. Fill in the **From Name** field (this value will be visible to message recipients).
5. Confirm the changes by clicking **Save**.

<figure><img src="/files/1EGvT5IgG2OvMyEhnWE6" alt=""><figcaption></figcaption></figure>

Once these steps are completed, the new address will be ready to use in API or SMTP integrations, and will also appear as an available sender in the **E-mail Campaigns** module.

### **Key parameters of the sandbox domain**

* The sandbox domain appears on the account after email address confirmation, completion of company details, and full account activation by the Customer Support Team.
* The domain is intended solely for initial connection validation. Entries within this domain cannot be deleted or edited.
* Sends from the sandbox domain should not be used as a measure of real deliverability, due to limited control over the reputation of the test infrastructure.
* Using the sandbox domain does not prevent you from adding and authorizing your own sending domain at any time.

### **Upgrading to a Paid Account**

An important aspect of upgrading your account to a paid plan is the change in sending infrastructure. At the point of switching to a paid model:

* The sandbox domain is permanently removed from the account.
* All email (From) addresses associated with the sandbox domain are deleted.
* Email campaigns (in the **E-mail Campaigns** module) that rely on the deleted sender addresses are automatically disconnected.

It is important to remember to carry out full authorization of your own domain and update the sender settings in your active campaigns. This ensures sending continuity and allows you to build an independent reputation with mail operators.