# File lib/vmail/contacts_extractor.rb, line 18
  def extract(limit = 500)
    open do |imap|
      set_mailbox_prefix
      mailbox = "[#@prefix]/Sent Mail"
      STDERR.puts "selecting #{mailbox}"
      imap.select(mailbox)
      STDERR.puts "fetching last #{limit} sent messages"
      all_uids = imap.uid_search('ALL')
      STDERR.puts "total messages: #{all_uids.size}"
      limit = [limit, all_uids.size].min
      STDERR.puts "extracting addresses from #{limit} of them"
      uids = all_uids[-limit ,limit]
      imap.uid_fetch(uids, ["FLAGS", "ENVELOPE"]).each do |fetch_data|
        recipients = fetch_data.attr["ENVELOPE"].to
        next unless recipients
        recipients.each do |address_struct|
          email = [address_struct.mailbox, address_struct.host].join('@') 
          name = address_struct.name
          if name 
            name = Mail::Encodings.unquote_and_convert_to(name, 'UTF-8') 
            yield %Q("#{name}" <#{email}>)
          else
            yield email
          end
        end
      end
    end
  end