Sinkbox

Overview

A high-level guide to what Sinkbox does, how signup works, and where to find the most important limits and policy details.

What Sinkbox does

Sinkbox captures emails, SMS messages, HTTP dumps, and other outgoing payloads from your applications so your team can inspect them safely in one inbox instead of sending them to real recipients.

Each project gets its own inbox, API credentials, and feature settings. You can review captured items, pin important ones, mark them as read, download payloads, and forward selected items when needed.

Getting started quickly

For many integrations, getting started is as simple as replacing one base URL or changing 1-3 config lines so your existing SDK or webhook target points to Sinkbox instead of the live service. Read the Ingestion page for SMTP, SMS, HTTP dumps, and drop-in service endpoints.

What happens when you sign up?

When instant signup is available, Sinkbox creates your organisation, your first project, a project API key, and a welcome inbox item straight away so you can start testing immediately.

If the current signup quota is full, you are placed on the waitlist instead. After you verify your email address, the team reviews your registration and gets in touch when access opens up.

Where to find answers

  • Roles and permissions explains organisation roles, project roles, and who can do what.
  • Retention and storage explains how long items are kept, what happens when storage fills up, and how pinned items behave.
  • Fair usage limits lists the service-wide rate limits for SMTP and HTTP ingestion.
  • Feature docs cover projects, ingestion, forwarding, downloads, public links, audit logs, and more.
  • Projects

    Organise projects to separate your inboxes.

  • Ingestion

    Store SMTP emails, SMS, HTTP dumps, and other payloads from 13+ external services.

  • Pinned items

    Pin important inbox entries so they stay protected from retention cleanup and easy to find.

  • Retention & storage

    Retention makes sure that inbox items are automatically deleted after a certain period to comply with data policies.

  • Downloads

    Download inbox payloads and attachments directly from the UI, in relevant formats.

  • Emergency Upgrade

    Temporarily raise plan limits for 30 days to handle an unexpected spike in volume.

  • Forwarding

    Forward selected inbox items to the outside world when needed.

  • Per-user read status

    Track read/unread state per teammate for advanced workflows.

  • Public inbox links

    Create secure public links for read-only sharing of inbox content. Choose between link access with or without authentication, and within or outside your organisation on higher plans.

  • Audit logs

    Review who accessed inbox content and when, created public links, invited users and much more for accountability and compliance.

Roles and permissions

What each organisation and project role can do.