```ruby
# Archive (and restore) emails in the database
class Archiving
  # Archive all the emails for a particular date (in UTC)
  # TODO Check that we're not trying to archive today's email
  def self.archive(date)
    t0 = date.to_datetime
    t1 = t0.next_day
    deliveries = Delivery.where(created_at: t0..t1).includes(:links, :click_events, :open_events, :address, :postfix_log_lines, {:email => [:from_address, :app]})

    FileUtils.mkdir_p("db/archive")

    # TODO bzip2 gives better compression but I had trouble with the Ruby gem for it
    Zlib::GzipWriter.open("db/archive/#{date}.tar.gz") do |gzip|
      Archive::Tar::Minitar::Writer.open(gzip) do |writer|
        deliveries.find_each do |delivery|
          content = ActionController::Base.new.render_to_string(partial: "deliveries/delivery.json.jbuilder", locals: {delivery: delivery})
          writer.add_file_simple("#{date}/#{delivery.id}.json", size: content.length, mode: 0600 ) {|f| f.write content}
        end
      end
    end
  end
end
```

Delete archived emails and don't archive if no emails
user
```ruby
# Archive (and restore) emails in the database
class Archiving
  # Archive all the emails for a particular date (in UTC)
  # TODO Check that we're not trying to archive today's email
  def self.archive(date)
    t0 = date.to_datetime
    t1 = t0.next_day
    deliveries = Delivery.where(created_at: t0..t1).includes(:links, :click_events, :open_events, :address, :postfix_log_lines, {:email => [:from_address, :app]})
    if deliveries.empty?
      puts "Nothing to archive for #{date}"
    else
      FileUtils.mkdir_p("db/archive")

      # TODO bzip2 gives better compression but I had trouble with the Ruby gem for it
      Zlib::GzipWriter.open("db/archive/#{date}.tar.gz") do |gzip|
        Archive::Tar::Minitar::Writer.open(gzip) do |writer|
          deliveries.find_each do |delivery|
            content = ActionController::Base.new.render_to_string(partial: "deliveries/delivery.json.jbuilder", locals: {delivery: delivery})
            writer.add_file_simple("#{date}/#{delivery.id}.json", size: content.length, mode: 0600 ) {|f| f.write content}
          end
        end
      end
      # The scary bit
      deliveries.destroy_all
    end
  end
end
```
assistant