Mailinator
Disposable email testing inboxes with public and private domains
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Advanced fake SMTP server for realistic email testing
smtp4dev provides a cross‑platform dummy SMTP/IMAP server with a rich web UI, API, TLS, authentication, multiple mailboxes, and tools for HTML validation and responsive email testing.
smtp4dev is a cross‑platform dummy SMTP and IMAP server designed for developers and QA engineers who need realistic email testing without sending real messages. It runs on any .NET 8 capable OS (Windows, Linux, macOS) and is also available as a Docker image for CI/CD pipelines.
The tool offers an advanced web interface with viewport switching to preview responsive designs, detailed SMTP session logs, and a built‑in MIME inspector. Through its OpenAPI/Swagger documented REST API you can programmatically manage messages, trigger relays, or simulate errors. Features such as TLS/SSL with auto‑generated certificates, authentication, multiple mailboxes with routing rules, and scripting make it suitable for production‑like testing scenarios.
Install via package managers or pull the official Docker container, configure ports for SMTP, IMAP, and the web UI, and start testing immediately. The flexible configuration lets you enable or disable components to match local development or automated test environments.
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Responsive email design verification
Render emails in various viewport sizes to ensure layout works on mobile and desktop clients
Automated CI email tests
Use the REST API to send test messages and assert content, headers, and delivery logs in pipeline runs
Multi‑mailbox routing simulation
Define rules to direct incoming messages to specific mailboxes, mimicking complex production routing
Error handling and failover testing
Inject scripted errors and TLS failures to validate application resilience
Yes, it offers implicit and STARTTLS modes and can auto‑generate self‑signed certificates.
An integrated IMAP server lets you retrieve, search, and delete messages using any standard IMAP client.
A ready‑to‑run Docker image is provided, suitable for CI/CD and containerized environments.
The OpenAPI/Swagger documented REST API allows programmatic sending, fetching, and managing messages.
Runs on any OS where .NET 8 is available, including Windows, Linux, and macOS.
Project at a glance
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