LesliMailer is the official application email engine for the Lesli Framework.

It provides a shared foundation for composing, previewing, and delivering email from Lesli applications.

• Shared Action Mailer foundation
• Background email delivery jobs
• Development mail previews
• Integration with Lesli accounts and users
• Reusable application email templates

• Try the online demo
• Run the Docker demo

• A Rails application with Lesli
• SQLite by default, or PostgreSQL when preferred by the host application

Add the engine to the host Rails application and prepare its database:

bundle add lesli_mailer
bin/rails db:prepare

Applications using Lesli's standard router mount LesliMailer automatically at /mailer:

# config/routes.rb
Rails.application.routes.draw do
    Lesli::Router.mount(self)
end

If the application does not use the standard Lesli router, mount the engine directly:

# config/routes.rb
Rails.application.routes.draw do
    mount LesliMailer::Engine => "/mailer"
end

Start Rails and visit http://127.0.0.1:3000/mailer:

bin/rails server

Clone LesliMailer into the host application's engines directory:

cd RailsApp
mkdir -p engines
git clone https://github.com/LesliTech/LesliMailer.git engines/LesliMailer

Reference the local engine from the host application's Gemfile:

gem "lesli_mailer", path: "engines/LesliMailer"

Install dependencies, prepare the host database, and start Rails:

bundle install
bin/rails db:prepare
bin/rails server

From a complete Lesli development workspace, run the engine test suite from the LesliMailer directory:

cd engines/LesliMailer
bin/rails test

• Lesli website
• Documentation
• Release notes
• Issue tracker
• Source code

• X: @LesliTech
• hello@lesli.tech
• https://www.lesli.tech

Copyright (c) 2026, Lesli Technologies, S. A.

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.

The complete license text is available in the license file.

The Open-Source SaaS Development Framework for Ruby on Rails.