A minor extension to Sidekiq's #delay_until to make delaying emails until a reasonable time easier...

delay_until_reasonable.rb

module Sidekiq
  module Extensions
    module Klass
      def delay_until_reasonable(options = {})
        reasonable_time = case Time.now.hour
          when 0..7
            Time.now.change(hour: 8)
          when 22..24
            Date.tomorrow.to_time.change(hour: 8)
          else
            Time.now
          end
        Proxy.new(DelayedMailer, self, options.merge(at: reasonable_time.to_f))
      end
    end
  end
end

Module.send(:include, Sidekiq::Extensions::Klass)

usage.rb

require 'delay_until_reasonable' # You can include this globally in your application.rb file.

# In a sidekiq job scheduled for... say 3am

invoices = Invoice.unpaid.overdue

invoices.each do |invoice|
  invoice.add_note("Your invoice is now overdue....")
  InvoiceMailer.delay_until_reasonable.payment_reminder(invoice.id)
end