send-mail/main.rb

#!/usr/bin/env ruby
# frozen_string_literal: true

require 'net/smtp'

# Inputs
address = ENV["INPUT_SERVER_ADDRESS"]
port = ENV["INPUT_SERVER_PORT"]
username = ENV["INPUT_USERNAME"]
password = ENV["INPUT_PASSWORD"]
subject = ENV["INPUT_SUBJECT"]
body = ENV["INPUT_BODY"]
to = ENV["INPUT_TO"]
from = ENV["INPUT_FROM"]

# Message
message = <<EOM
Subject: #{subject}
From: #{from} <#{username}>

#{body}
EOM

# Send
begin
  smtp = Net::SMTP.new(address, port.to_i)
  smtp.enable_tls
  smtp.start(address, username, password, :login)
  smtp.send_message(message, username, to.split(","))
rescue StandardError => e
  puts "Error: #{e.message}"
  exit 1
end