You could install a second machine for testing, but as you say, it would be a large project. It would also be possible to install a second LISTSERV instance on the current machine, but it may not be a much smaller project in practice. You'd have to create a new home directory for the test instance, compile new binaries with the correct spool path, run LISTSERV under a different user id, alter /etc/aliases to route mail for the new LISTSERV user id to the correct copy of lsv_amin, set up a new virtual host in apache, change the test LISTSERV's TCP/GUI port to something other than the default, and probably make other changes of which I'm not thinking off the top of my head. It would be possible, but kind of a pain. Personally, I would just make a copy of your current ~/listserv directory, run the standard 'make update' during off-hours, do some testing, and roll back to the copy if you don't like the result. It would almost certainly be less headache... -- Liam