# rnwood/smtp4dev

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3,817 stars · 413 forks · C# · bsd-3-clause

## Links

- GitHub: https://github.com/rnwood/smtp4dev
- awesome-repositories: https://awesome-repositories.com/repository/rnwood-smtp4dev.md

## Topics

`linux` `macosx` `smtp-server` `smtp4dev` `windows`

## Description

smtp4dev is a suite of tools featuring a mock SMTP server that intercepts outgoing email traffic and stores messages for inspection instead of delivering them to recipients. It includes a web-based viewer for inspecting email metadata, raw source code, and MIME structures, alongside a responsive email previewer that simulates how HTML emails appear across different viewport sizes and device layouts.

The project provides a traffic analyzer to log protocol interactions and session data for debugging delivery failures. It also operates as a TLS SMTP server, supporting encrypted connections via TLS and SSL to mimic secure production environments.

The system covers broader capabilities for local SMTP testing, email template development, and automated email integration. It offers both a web-based viewer and a terminal user interface for managing and monitoring intercepted mail traffic in headless environments.

## Tags

### Testing & Quality Assurance

- [SMTP Server Mocks](https://awesome-repositories.com/f/testing-quality-assurance/smtp-server-mocks.md) — Provides a mock SMTP server to intercept and verify outgoing emails without delivering them to real users.
- [Email Testing Tools](https://awesome-repositories.com/f/testing-quality-assurance/general-testing-utilities/test-utilities-assertions/email-testing-tools.md) — Provides a web interface to retrieve and verify intercepted emails for automated integration tests. ([source](https://github.com/rnwood/smtp4dev/tree/master/docs/))

### Part of an Awesome List

- [Mock Integration Testing](https://awesome-repositories.com/f/awesome-lists/media/email-integration/mock-integration-testing.md) — Allows programmatic validation that applications trigger the correct emails during integration tests.

### Data & Databases

- [Web-Based Viewers](https://awesome-repositories.com/f/data-databases/database-data-viewers/web-based-viewers.md) — Ships a browser-based interface for inspecting intercepted emails, metadata, and MIME structures.

### Networking & Communication

- [Email Inspection Dashboards](https://awesome-repositories.com/f/networking-communication/email-administrative-interfaces/email-inspection-dashboards.md) — Provides a dashboard for reviewing email metadata, raw source code, and MIME structures. ([source](https://cdn.jsdelivr.net/gh/rnwood/smtp4dev@master/README.md))
- [Mail Protocol Implementations](https://awesome-repositories.com/f/networking-communication/mail-servers/mail-protocol-implementations.md) — Implements the standard SMTP protocol to handle handshakes and capture outgoing mail traffic.
- [SMTP Message Interception](https://awesome-repositories.com/f/networking-communication/smtp-server-implementations/smtp-message-interception.md) — Captures outgoing SMTP traffic in local environments to inspect messages without delivery. ([source](https://github.com/rnwood/smtp4dev/tree/master/docs/))
- [Network Traffic Analyzers](https://awesome-repositories.com/f/networking-communication/network-traffic-analyzers.md) — Logs detailed protocol interactions and session data to debug SMTP delivery failures.

### Development Tools & Productivity

- [Terminal User Interfaces](https://awesome-repositories.com/f/development-tools-productivity/terminal-user-interfaces.md) — Offers an interactive terminal-based interface to monitor server status and modify settings. ([source](https://github.com/rnwood/smtp4dev/tree/master/docs/))

### Security & Cryptography

- [SSL/TLS Connection Security](https://awesome-repositories.com/f/security-cryptography/ssl-tls-connection-security.md) — Implements secure transport layers using TLS/SSL to encrypt data transmitted between email clients and the mock server. ([source](https://github.com/rnwood/smtp4dev/tree/master/docs/))
- [SMTP TLS Encryption](https://awesome-repositories.com/f/security-cryptography/ssl-tls-connection-security/mqtt-tls-encryption/smtp-tls-encryption.md) — Provides a mock SMTP server that supports encrypted connections via TLS and SSL to mimic secure production environments.
- [Transport Layer Encryption](https://awesome-repositories.com/f/security-cryptography/transport-layer-encryption.md) — Secures communication between email clients and the server using TLS and SSL encryption.

### System Administration & Monitoring

- [Protocol Debugging Logs](https://awesome-repositories.com/f/system-administration-monitoring/protocol-debugging-logs.md) — Ships detailed protocol logging and session data to troubleshoot SMTP delivery failures and connection issues. ([source](https://cdn.jsdelivr.net/gh/rnwood/smtp4dev@master/README.md))
- [Wire Protocol Debugging](https://awesome-repositories.com/f/system-administration-monitoring/wire-protocol-debugging.md) — Analyzes raw MIME structures and session logs to troubleshoot email formatting and connection failures.

### User Interface & Experience

- [Responsive Layout Previews](https://awesome-repositories.com/f/user-interface-experience/content-previewing/responsive-layout-previews.md) — Previews HTML emails using adjustable viewport sizes to verify responsive design compatibility. ([source](https://cdn.jsdelivr.net/gh/rnwood/smtp4dev@master/README.md))
- [Email Template Previews](https://awesome-repositories.com/f/user-interface-experience/email-template-previews.md) — Enables local rendering and visual verification of HTML email layouts across various screen sizes.
- [Viewport Simulation](https://awesome-repositories.com/f/user-interface-experience/html-content-processing/code-to-html-rendering/viewport-simulation.md) — Simulates email layouts by wrapping HTML content in adjustable containers to test responsive design.
- [Terminal User Interfaces](https://awesome-repositories.com/f/user-interface-experience/terminal-user-interfaces.md) — Provides a text-based user interface for server administration and monitoring in terminal environments.