email_batch.rb

class EmailBatch
  attr_reader :messages

  delegate :<<, to: :messages

  def initialize(messages = [])
    @messages = messages
  end

  def deliver_now
    messages.each { |msg| Mail.inform_interceptors(msg) }    
    result = client.deliver_messages(messages)
    messages.each { |msg| Mail.inform_observers(msg) }

    result
  end

  def deliver_later
    fail NotImplementedError, 'Delayed delivery is not implemented for batches.'
  end

  private

  def client
    Postmark::ApiClient.new(config[:api_key] || config[:api_token], config)
  end

  def config
    ActionMailer::Base.postmark_settings
  end
end