    # File lib/vmail/imap_client.rb, line 567
        def copy_to(uid_set, mailbox)
          uid_set = uid_set.split(',').map(&:to_i)
          if mailbox_aliases[mailbox]
            mailbox = mailbox_aliases[mailbox]
          end
          create_if_necessary mailbox
          log "copying #{uid_set.inspect} to #{mailbox}"
          spawn_thread_if_tty do
            log @imap.uid_copy(uid_set, mailbox)
            log "copied uid_set #{uid_set.inspect} to #{mailbox}"
          end
        end