If it is necessary to change NA-NET databases ``by hand'', the NA-NET system should be suspended. In the directory /usr/local/na-net there is a script called na-net.sh; this does nothing but exit with a ``temporary failure'' status. If the normal NA-NET binary is moved aside and the na-net.sh file put in its place, sendmail will queue any messages for NA-NET and keep trying every half hour or so. After renaming the na-net.sh file, wait a few minutes so that any NA-NET processes can finish up before editing the database. After making whatever changes are necessary, don't forget to rename the real NA-NET program back to na-net.