extract_addresses_from_gmail.rb

require 'gmail'
require 'csv'
require 'io/console'

class EmailExtractor
  def self.run
    new.run
  end

  def initialize
    printf "Enter your gmail username: "
    username = gets.chomp
    printf "Enter you password: "
    password = STDIN.noecho(&:gets).chomp
    @gmail = Gmail.new(username, password)
  end

  def run
    printf "\nConnecting..."
    printf "\nCollecting emails..."

    all_messages
    printf "\nWriting to CSV..."

    CSV.open("emails_test.csv", "w+") do |csv|
      csv << %w[emails]
      all_messages.uniq.each_with_index do |email, i|
        csv << [email]
        printf '.' if (i%15).zero?
      end
    end

    printf "\nWriting complete."
    printf "\nLogging you out..."

    gmail.logout
    printf "\nGoodbye.\n"
  end

  private
  attr_reader :gmail

  def all_messages
    sent + all_mail
  end

  def all_mail
    @all_mail ||= gmail.mailbox("[Gmail]/All Mail").emails.map(&:from).uniq
  end

  def sent
    @sent ||= gmail.mailbox("[Gmail]/Sent Mail").emails.map(&:to).uniq
  end
end

EmailExtractor.run