I suggest using a test instance of LISTSERV (installed on another server or,
if not possible, in another directory tree) pointing to a different table
that is created by cloning the original table. This way you can test as much
as you want without worries.

A lot of customers use Oracle, perhaps not the exact same version that you
are using. Unfortunately we cannot test every version of every database,
there are just too many. I think we test against 10g for Oracle. The most
important is actually not the version of the DBMS but the version of the
ODBC driver. It is extremely rare to have a problem after upgrading the DBMS
itself, since LISTSERV uses the simplest possible syntax and database
vendors are always very careful about the compatibility of basic DBMS
commands. But ODBC drivers do a lot of "dirty work" to present an ODBC
interface to a database that works completely differently internally.
Sometimes they have to use undocumented features of the DBMS.

If testing on another server, you can try upgrading to the latest ODBC
driver (Oracle's ODBC drivers are usually backward-compatible, but
double-check before you try). I don't have any special reasons to think that
it will solve the problem, but in the past there have been cases where
mysterious problems disappeared after upgrading the ODBC driver.

  Eric