MiniSmtpServer is a small and easily customizable SMTP server. It is designed mainly to be integrated into other systems that will decide what to do with the mail that is received. By default mini-smtp-server operates as a black-hole and does not do anything with the mail being sent to it… Don’t let that discourage you though, as MiniSmtpServer is designed to be extremely easy to customize which makes it fit more easily into your system!

To run the default server simply use:

# Create a new server instance listening at 127.0.0.1:2525
# and accepting a maximum of 4 simultaneous connections
server = MiniSmtpServer.new(2525, "127.0.0.1", 4)

# Start the server
server.start

# ...
# serving requests & doing other work here
# ...

# Shutdown the server without interrupting any connections:
server.shutdown
while(server.connections > 0)
  sleep 0.01
end
server.stop
server.join

For convenience MiniSmtpServer is packaged as a RubyGem, to install it simply enter the following at your command line:

gem install mini-smtp-server

MiniSmtpServer is designed to be easy to customize via subclassing. Simply subclass the ‘MiniSmtpServer` class and re-define the `new_message_event` event handler:

# This is an SMTP server that logs all
# the messages it receives to STDOUT
class StdoutSmtpServer < MiniSmtpServer

  def new_message_event(message_hash)
    puts "# New email received:"
    puts "-- From: #{message_hash[:from]}"
    puts "-- To:   #{message_hash[:to]}"
    puts "--"
    puts "-- " + message_hash[:data].gsub(/\r\n/, "\r\n-- ")
    puts
  end

end

Then create an instance of your new server and run it like you would normally:

server = StdoutSmtpServer.new
server.start
server.join

The possibilities are endless, and easy to implement! Want all your email stored in a database? No worries:

class DatabaseSmtpServer < MiniSmtpServer
  def new_message_event(message_hash)
    # Imagine we have an ActiveRecord model named 'Email'
    Email.create(message_hash)
  end
end

# Presto!

If you have a great example of something you’ve done with MiniSmtpServer let me know and I will add it here!

Author

Aaron Gough

MiniSmtpServer is based on code originally written by Peter Cooper

Copyright © 2010 Aaron Gough (thingsaaronmade.com), released under the MIT license