MailHog

Web and API based SMTP testing

15,110

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Quick Overview

MailHog is an email testing tool for developers. It provides a fake SMTP server that captures outgoing emails from your application, allowing you to view and test them without actually sending them to real recipients. MailHog offers a web interface for easy management and inspection of captured emails.

Pros

Easy to set up and use, with minimal configuration required
Cross-platform compatibility (Windows, macOS, Linux)
Provides both web and API interfaces for email management
Supports SMTP and HTTP protocols for sending mail

Cons

Limited email rendering capabilities compared to real email clients
May not fully simulate all email delivery scenarios
No built-in load testing or high-volume email handling features
Lacks advanced features like email authentication testing (SPF, DKIM, DMARC)

Getting Started

Install MailHog:

# Using Go
go install github.com/mailhog/MailHog@latest

# Or download a pre-built binary from GitHub releases

Run MailHog:
```
MailHog
```
Configure your application to use MailHog as the SMTP server:
```
SMTP_HOST=localhost
SMTP_PORT=1025
```
Access the web interface at http://localhost:8025 to view captured emails.

Competitor Comparisons

mailcatcher

6,646

Catches mail and serves it through a dream.

Pros of MailCatcher

Written in Ruby, making it easier to integrate with Ruby-based projects
Simpler setup process, especially for Ruby developers
Lightweight and consumes fewer system resources

Cons of MailCatcher

Less actively maintained compared to MailHog
Fewer features and customization options
Limited support for non-Ruby environments

Code Comparison

MailCatcher (Ruby):

require 'mail_catcher'

MailCatcher.start(
  smtp_ip: '0.0.0.0',
  smtp_port: 1025,
  http_ip: '0.0.0.0',
  http_port: 1080
)

MailHog (Go):

import "github.com/mailhog/MailHog/config"

cfg := &config.Config{
    SMTPBindAddr: "0.0.0.0:1025",
    APIBindAddr:  "0.0.0.0:8025",
    UIBindAddr:   "0.0.0.0:8025",
}

Both MailCatcher and MailHog serve as SMTP testing tools, but MailHog offers more features, better cross-platform support, and is more actively maintained. MailCatcher may be preferred in Ruby-centric environments due to its simplicity and easy integration. However, for more comprehensive email testing and broader language support, MailHog is generally the recommended choice.

inbucket

1,868

Disposable webmail server (similar to Mailinator) with built in SMTP, POP3, RESTful servers; no DB required.

Pros of Inbucket

Supports multiple storage backends (memory, filesystem, SQLite)
Provides a REST API for programmatic access to messages
Offers a web-based user interface for easy message viewing and management

Cons of Inbucket

Less actively maintained compared to MailHog
Fewer configuration options and customization features
Limited cross-platform support (primarily focused on Linux and macOS)

Code Comparison

MailHog (Go):

func CreateMessage(message *data.SMTPMessage) ([]byte, error) {
    msg := gomail.NewMessage()
    msg.SetHeader("From", message.From)
    msg.SetHeader("To", message.To...)
    msg.SetHeader("Subject", message.Subject)
    msg.SetBody("text/plain", message.Data)
    return msg.Bytes()
}

Inbucket (Go):

func (m *Message) AsEmail() (*email.Email, error) {
    e := &email.Email{}
    e.From = m.From
    e.To = m.To
    e.Subject = m.Subject
    e.Text = []byte(m.Text)
    e.HTML = []byte(m.HTML)
    return e, nil
}

Both projects are written in Go and provide similar functionality for handling email messages. MailHog offers a more feature-rich and actively maintained solution, while Inbucket provides flexibility in storage options and a REST API. The choice between the two depends on specific project requirements and desired features.

mailpit

7,456

An email and SMTP testing tool with API for developers

Pros of Mailpit

Actively maintained with regular updates
Supports SMTP authentication
Offers a more modern and responsive web UI

Cons of Mailpit

Fewer configuration options compared to MailHog
Less established community and ecosystem

Code Comparison

MailHog configuration example:

cfg := &config.Config{
    SMTPBindAddr: "0.0.0.0:1025",
    APIBindAddr:  "0.0.0.0:8025",
    Hostname:     "mailhog.example",
}

Mailpit configuration example:

config := &Config{
    SMTPListen:   "0.0.0.0:1025",
    HTTPListen:   "0.0.0.0:8025",
    WebUIPath:    "/",
    AuthFile:     "auth.json",
}

Both projects serve similar purposes as email testing tools, but Mailpit offers some modern improvements and active development. MailHog has a larger user base and more extensive documentation. The code examples show similar configuration approaches, with Mailpit including additional options like authentication file support.

smtp4dev

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smtp4dev - the fake smtp email server for development and testing

Pros of smtp4dev

Built with .NET Core, offering cross-platform compatibility and better performance
Supports IMAP protocol in addition to SMTP, allowing for more comprehensive email testing
Provides a more modern and feature-rich web interface with real-time updates

Cons of smtp4dev

Requires .NET Core runtime, which may not be available on all systems
Has a more complex setup process compared to MailHog's single binary deployment
Less widespread adoption and community support than MailHog

Code Comparison

MailHog (Go):

func CreateSMTPListener(cfg *config.Config) (net.Listener, error) {
    addr, err := net.ResolveTCPAddr("tcp4", cfg.SMTPBindAddr)
    if err != nil {
        return nil, err
    }
    return net.ListenTCP("tcp4", addr)
}

smtp4dev (C#):

public void ConfigureServices(IServiceCollection services)
{
    services.AddSingleton<ISmtpServer>(sp => 
        new SmtpServer.SmtpServer(new SmtpServerOptionsBuilder()
            .ServerName("smtp4dev")
            .Port(25)
            .Build()));
}

Both projects aim to provide local SMTP testing environments, but smtp4dev offers more features and protocols at the cost of a slightly more complex setup. MailHog remains popular due to its simplicity and ease of use across various platforms.

FakeSMTP

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Dummy SMTP server with GUI for testing emails in applications easily.

Pros of FakeSMTP

Lightweight and easy to set up, requiring minimal configuration
Written in Java, making it platform-independent and easily integrated into Java-based projects
Provides a simple GUI for viewing received emails

Cons of FakeSMTP

Limited features compared to MailHog, lacking advanced filtering and API capabilities
Less active development and community support
No built-in web interface for remote access to captured emails

Code Comparison

MailHog (Go):

func CreateSMTP(cfg *config.Config, storage storage.Storage) *SMTPServer {
    return &SMTPServer{
        config:  cfg,
        storage: storage,
    }
}

FakeSMTP (Java):

public class SMTPServer {
    private ServerSocket serverSocket;
    private boolean stopped = false;

    public void start(int port) throws IOException {
        serverSocket = new ServerSocket(port);
    }
}

Both projects aim to provide fake SMTP servers for testing purposes, but MailHog offers a more feature-rich solution with a web interface and API support. FakeSMTP, on the other hand, provides a simpler, Java-based alternative that may be preferable for Java developers or those seeking a lightweight solution. MailHog's codebase is in Go, while FakeSMTP is written in Java, which may influence the choice depending on the development environment and integration requirements.

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README

MailHog

Inspired by MailCatcher, easier to install.

Download and run MailHog
Configure your outgoing SMTP server
View your outgoing email in a web UI
Release it to a real mail server

Built with Go - MailHog runs without installation on multiple platforms.

Overview

MailHog is an email testing tool for developers:

Configure your application to use MailHog for SMTP delivery
View messages in the web UI, or retrieve them with the JSON API
Optionally release messages to real SMTP servers for delivery

Installation

Manual installation

Download the latest release for your platform. Then read the deployment guide for deployment options.

MacOS

brew update && brew install mailhog

Then, start MailHog by running mailhog in the command line.

Debian / Ubuntu Go < v1.18

sudo apt-get -y install golang-go
go get github.com/mailhog/MailHog

Go >= v1.17 (Debian Bookworm)

sudo apt-get -y install golang-go
go install github.com/mailhog/MailHog@latest

Then, start MailHog by running /path/to/MailHog in the command line.

E.g. the path to Go's bin files on Ubuntu is ~/go/bin/, so to start the MailHog run:

~/go/bin/MailHog

FreeBSD

pkg install mailhog
sysrc mailhog_enable="YES"
service mailhog start

Docker

Run it from Docker Hub or using the provided Dockerfile

Configuration

Check out how to configure MailHog, or use the default settings:

the SMTP server starts on port 1025
the HTTP server starts on port 8025
in-memory message storage

Features

See MailHog libraries for a list of MailHog client libraries.

ESMTP server implementing RFC5321
Support for SMTP AUTH (RFC4954) and PIPELINING (RFC2920)
Web interface to view messages (plain text, HTML or source)
- Supports RFC2047 encoded headers
Real-time updates using EventSource
Release messages to real SMTP servers
Chaos Monkey for failure testing
- See Introduction to Jim for more information
HTTP API to list, retrieve and delete messages
- See APIv1 and APIv2 documentation for more information
HTTP basic authentication for MailHog UI and API
Multipart MIME support
Download individual MIME parts
In-memory message storage
MongoDB and file based storage for message persistence
Lightweight and portable
No installation required

sendmail

mhsendmail is a sendmail replacement for MailHog.

It redirects mail to MailHog using SMTP.

You can also use MailHog sendmail ... instead of the separate mhsendmail binary.

Alternatively, you can use your native sendmail command by providing -S, for example:

/usr/sbin/sendmail -S mail:1025

For example, in PHP you could add either of these lines to php.ini:

sendmail_path = /usr/local/bin/mhsendmail
sendmail_path = /usr/sbin/sendmail -S mail:1025

Web UI

Screenshot of MailHog web interface

Contributing

MailHog is a rewritten version of MailHog, which was born out of M3MTA.

Clone this repository to $GOPATH/src/github.com/mailhog/MailHog and type make deps.

See the Building MailHog guide.

Requires Go 1.4+ to build.

Run tests using make test or goconvey.

If you make any changes, run go fmt ./... before submitting a pull request.

Licence

Released under MIT license, see LICENSE for details.

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