awesome-repositories.com
Blog
MCP
awesome-repositories.com

Discover the best open-source repositories with AI-powered search.

ExploreCurated searchesOpen-source alternativesSelf-hosted softwareBlogSitemap
ProjectMCP serverAboutHow we rankPress
LegalPrivacyTerms
© 2026 Bringes Technology SRL·VAT RO45896025·hello@awesome-repositories.com
rnwood avatar

rnwood/smtp4dev

0
View on GitHub↗
3,817 stars·413 forks·C#·bsd-3-clause·8 views

Smtp4dev

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.

Features

  • SMTP Server Mocks - Provides a mock SMTP server to intercept and verify outgoing emails without delivering them to real users.
  • Mock Integration Testing - Allows programmatic validation that applications trigger the correct emails during integration tests.
  • Web-Based Viewers - Ships a browser-based interface for inspecting intercepted emails, metadata, and MIME structures.
  • Email Inspection Dashboards - Provides a dashboard for reviewing email metadata, raw source code, and MIME structures.
  • Mail Protocol Implementations - Implements the standard SMTP protocol to handle handshakes and capture outgoing mail traffic.
  • SMTP Message Interception - Captures outgoing SMTP traffic in local environments to inspect messages without delivery.
  • Terminal User Interfaces - Offers an interactive terminal-based interface to monitor server status and modify settings.
  • Network Traffic Analyzers - Logs detailed protocol interactions and session data to debug SMTP delivery failures.
  • SSL/TLS Connection Security - Implements secure transport layers using TLS/SSL to encrypt data transmitted between email clients and the mock server.
  • SMTP TLS Encryption - Provides a mock SMTP server that supports encrypted connections via TLS and SSL to mimic secure production environments.
  • Transport Layer Encryption - Secures communication between email clients and the server using TLS and SSL encryption.
  • Protocol Debugging Logs - Ships detailed protocol logging and session data to troubleshoot SMTP delivery failures and connection issues.
  • Wire Protocol Debugging - Analyzes raw MIME structures and session logs to troubleshoot email formatting and connection failures.
  • Email Testing Tools - Provides a web interface to retrieve and verify intercepted emails for automated integration tests.
  • Responsive Layout Previews - Previews HTML emails using adjustable viewport sizes to verify responsive design compatibility.
  • Email Template Previews - Enables local rendering and visual verification of HTML email layouts across various screen sizes.
  • Viewport Simulation - Simulates email layouts by wrapping HTML content in adjustable containers to test responsive design.
  • Terminal User Interfaces - Provides a text-based user interface for server administration and monitoring in terminal environments.
  • Data and Networking - Fake SMTP server for development and testing.

Star history

Star history chart for rnwood/smtp4devStar history chart for rnwood/smtp4dev

How this analysis was created: This summary and feature list were written by an AI model that read the project's README and public documentation pages. Each feature links to the documentation it came from; stars, license and language come straight from the GitHub API. The model does not read the source code, and the analysis is refreshed when the project is re-analysed. Learn more on our About page.

AI search

Explore more awesome repositories

Describe what you need in plain English — the AI ranks thousands of curated open-source projects by relevance.

Start searching with AI

Open-source alternatives to Smtp4dev

Similar open-source projects, ranked by how many features they share with Smtp4dev.
  • sj26/mailcatchersj26 avatar

    sj26/mailcatcher

    6,762View on GitHub↗

    Mailcatcher is a local email development proxy and SMTP server mock designed to intercept outgoing emails during development. It acts as a network bridge that catches outbound mail on a specified port and displays it in a web-based inspector instead of delivering messages to real recipients. The tool provides a web-based email viewer for reviewing HTML, plain text, and raw source content, along with an interface for inspecting headers and downloading attachments. It utilizes a RESTful JSON API to serve captured mail as structured data to the browser interface. The system includes a TCP socke

    Rubydevelopmentdevtoolsmail
    View on GitHub↗6,762
  • axllent/mailpitaxllent avatar

    axllent/mailpit

    8,764View on GitHub↗

    Mailpit is an SMTP mail testing server and web-based email inbox designed to intercept and store outgoing emails for development and integration testing without delivering them to real recipients. It functions as an SMTP mocking tool and relay gateway, allowing users to capture mail traffic and view it through a browser interface. The project distinguishes itself by providing tools for SMTP server simulation, including the ability to inject failure codes to test application resilience. It also includes an email compatibility analyzer that validates HTML rendering, checks link integrity, and s

    Goemail-testinggogolang
    View on GitHub↗8,764
  • mailhog/mailhogmailhog avatar

    mailhog/MailHog

    15,784View on GitHub↗

    MailHog is an email testing tool that functions as a local SMTP server to capture outgoing messages during the development process. By intercepting SMTP traffic, it allows developers to verify email content, headers, and attachments without transmitting messages to actual external recipients. Captured data is stored in an in-memory buffer, ensuring that sensitive information remains accessible for inspection through a dedicated web-based dashboard. The platform distinguishes itself by incorporating network simulation capabilities, which allow for the injection of artificial delays or connecti

    Go
    View on GitHub↗15,784
  • sta/websocket-sharpsta avatar

    sta/websocket-sharp

    6,067View on GitHub↗

    websocket-sharp is a C# library implementation of the WebSocket protocol used for building bidirectional client and server applications. It enables real-time data exchange between endpoints via persistent connections. The library provides specialized networking capabilities, including SSL encrypted networking for secure transport and certificate validation. It also features HTTP proxy tunneling to route traffic through intermediary servers using basic or digest authentication. The project covers a broad range of capabilities, including the implementation of both WebSocket clients and servers

    C#
    View on GitHub↗6,067
See all 30 alternatives to Smtp4dev→

Frequently asked questions

What does rnwood/smtp4dev do?

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.

What are the main features of rnwood/smtp4dev?

The main features of rnwood/smtp4dev are: SMTP Server Mocks, Mock Integration Testing, Web-Based Viewers, Email Inspection Dashboards, Mail Protocol Implementations, SMTP Message Interception, Terminal User Interfaces, Network Traffic Analyzers.

What are some open-source alternatives to rnwood/smtp4dev?

Open-source alternatives to rnwood/smtp4dev include: sj26/mailcatcher — Mailcatcher is a local email development proxy and SMTP server mock designed to intercept outgoing emails during… axllent/mailpit — Mailpit is an SMTP mail testing server and web-based email inbox designed to intercept and store outgoing emails for… mailhog/mailhog — MailHog is an email testing tool that functions as a local SMTP server to capture outgoing messages during the… sta/websocket-sharp — websocket-sharp is a C# library implementation of the WebSocket protocol used for building bidirectional client and… gcla/termshark — Termshark is a terminal-based network packet analyzer and protocol flow inspector. It serves as a keyboard-driven… helix-editor/helix — Helix is a terminal-based modal text editor designed for efficient code manipulation and navigation. It centers on a…