FakeSMTP

📨 Fake-SMTP

FakeSMTP is a Free Fake SMTP Server for testing emails in applications easily.

You can use it as a normal SMTP server in your applications. All emails will be intercepted and processed by this software.

Origin

This project aims to be a successor of the identically named project by Gautier MECHLING aka Nilhem: https://github.com/Nilhcem/FakeSMTP

✌ Thank you very much for your effort and inspiration! ✌

Download

You can find the latest and greates release in the github releases section.

Setup

Native

Requirements

• Java SE JRE 7 (headless will suffice as there is no GUI)

Installation

curl -Lo /opt/fakesmtp.jar https://github.com/thomas-mc-work/fakesmtp/releases/download/fakesmtp-3.0/fakesmtp-3.0.jar

You might want to define an alias somewhere (e.g. in $HOME/.bashrc) to shorten the execution line:

alias fakesmtp='java -jar /opt/fakesmtp.jar'

Create system.d service

First you need to create the unit file in /etc/systemd/system/unit:

[Unit]
Description=FakeSMTP server

[Service]
ExecStart=/usr/bin/java -jar /opt/fakesmtp.jar -o /data/mail-output
Restart=always

Next you have to reload the systemd settings:

systemctl reload fakesmtp

Then you can check the status, start the service and finally enable it for autostart:

systemctl status fakesmtp
systemctl start fakesmtp
systemctl enable fakesmtp

Docker

This image is not (yet) on docker hub, so you need to create it locally:

docker build -t tmcw/fakesmtp:latest github.com/thomas-mc-work/fakesmtp
docker run -d -p 2525:25 -v /path/to/mail-output:/output tmcw/fakesmtp

The default behaviour is to write all emails to /output. You can override this parameter of course.

Usage

CLI usage:

Usage: java -jar fakesmtp-jar [-hvV] [-b=<bindAddress>] [-c=<cliCommand>]
                              [-o=<outputPath>] [-p=<portNumber>]
                              [-r=<relayDomains>]...
Fake SMTP server with configurable output.
  -b, --bind-address=<bindAddress>
                              IP address or hostname to bind to.
  -c, --cli-command=<cliCommand>
                              Full path to an executable in the file system
  -h, --help                  Print usage help
  -o, --output-path=<outputPath>
                              Emails output directory
  -p, --port=<portNumber>     SMTP port number
  -r, --relay-domains=<relayDomains>
                              Comma separated email domain(s) for which relay
                                is accepted. If specified, relays only emails
                                matching these domain(s), dropping (not saving)
                                others (default: allow any domain)
  -v, --verbose               Enable DEBUG logging
  -V, --version               print version

CommandLine script Handler

The selected script via -c can make use of these environment variables:

• $MAIL_FROM
• $MAIL_TO
• $MAIL_SUBJECT
• $MAIL_BODY

Example usage: SMTP2XMPP gateway

A sendxmpp config file ($HOME/.sendxmpprc):

user@host s3cr3t-password

A shell script:

#!/usr/bin/env sh

printf "From: ${MAIL_FROM}
To: ${MAIL_TO}
Subject: ${MAIL_SUBJECT}
Body:

${MAIL_BODY}" | sendxmpp "user@xmpp-host.org" -s "email received" -r   "cli client"

Starting the STMP server:

java -jar fakesmtp.jar -c "/path/to/the-wrapper-script.sh"

Example usage: observe all mails

You can replace the former existing GUI by this cli command:

inotifywait -mre create "/path/to/output" | while read dir event file; do
    echo "°°°°°°°°°°°"
    cat "${dir}${file}"
done

Metrics

• Memory footprint: ~23 MB
• Jar file size: 1.6 MB
• Startup time: ~0.27 s

EML viewers

You can use the following open tools to view the eml files:

• Mozilla Thunderbird heavyweight (There is no need to create an account even though it's asking for it)
• Gnome Evolution heavyweight
• mpack lightweight command line

Development

First of all: Contributions are welcome!

Implement a new mail handler

You can simply implement the org.tmcw.fakesmtp.spi.MailHandler interface to add a new behaviour to received emails. You also nedd to add your handler to the mailHandlerList somewhere here.

Testing

There are three test layers that you can use to verify your changes:

• Unit Test: mvn test
• Mutation Test (testing the quality of the unit tests): mvn -Dthreads=4 -DwithHistory org.pitest:pitest-maven:mutationCoverage
• Integration Test: mvn failsafe:integration-test failsafe:verify
• System Test: ./run-st.sh (requires the docker + jq tools in your system)

If you plan to implement a feature and you feel unable to provide the tests – that's ok! I can try to add them later.

I can't import the project on Eclipse IDE

Run the following command to create eclipse project files:

mvn eclipse:eclipse

Alternatives

From the former FakeSMTP author:

FakeSMTP was created because we couldn't find any free (as in freedom) and cross-platform SMTP server with GUI for testing emails in applications or websites. Listed below are some greats alternatives to Fake SMTP:

• GreenMail
  • ± has a nice GUI
  • ➕ written in Java
  • ➕ Open source
• FakeSMTP legacy
  • ± has a nice GUI
  • ➕ written in Java
  • ➕ Open source
  • ➕ Lightweight
  • ➖ output is not configurable
• SMTP4dev
  • ➕ Nice features
  • ➕ Open source
  • ➖ Written for Windows in .net
• DevNull SMTP
  • ➕ Lightweight
  • ➖ Closed source
  • ➕ Written in Java 1.4 (cross platform)

Changes from FakeSMTP

• migration to Java SE 7
• removed the GUI
• make the output processing modular
• changed the output filename timestamp format to ISO alike
• add four testing layers for better quality control

Developer related:

• lots of code cleanups and simplifications
• remove some unused dependencies
• many refactorings (e.g. removed enum based singletons)
• removed the site generation