An inbox is a dedicated email receiver inside a project. Point your application at an inbox and, instead of being delivered, every message it sends is captured in MailSandbox where you can preview, inspect and share it.

Each inbox has its own isolated credentials, so you can use separate inboxes for different environments, applications or features — for example one for staging and one for acceptance.

To create a new inbox in your project:

1. Open the project and go to "Inboxes"
2. Click "New Inbox"
3. Enter a descriptive name, for example "Staging" or "Acceptation"
4. Choose whether the inbox is private or shared
5. Click "Create" to generate the inbox and its credentials

Private & shared inboxes

Every inbox has a visibility setting:

• Private — only you can see the messages it captures. Ideal for your own local or development testing.
• Shared — everyone with access to the project can see the captured email, so your whole team can review it together.

When an inbox is created, MailSandbox automatically generates a unique set of credentials for it:

• API key — prefixed with "ms_", used to send email over the API
• SMTP username — also prefixed with "ms_", used as the SMTP login
• SMTP password — an auto-generated secret for SMTP authentication

You can find these any time on the inbox's Configuration screen, together with copy-paste code samples for your stack. See SMTP configuration and API integration for the details.

Open an inbox to browse the messages it has captured. From the message list and toolbar you can:

• Search messages and filter between all and unread
• Open a message to preview it and inspect its source, headers, HTML compatibility and spam score
• Mark everything as read
• Empty the inbox to remove every captured message

Once a message is open you can preview it across screen sizes and share it with clients for review.