> Is there a document referencing the changes/enhancements between
> release version of LISTSERV software (ex, 1.8c to 1.8d)?

http://www.lsoft.com/manuals/1.8d/index.html

toward the bottom:  two links  to access:

Release notes for LISTSERV version 1.8d (via FTP):

     List Owner's Release Notes for LISTSERV 1.8d
     Maintainer's Release Notes for LISTSERV 1.8d

ad there is also quite a bit of info in the 1.8d manuals on what was
changed.

  ...Cleo  [log in to unmask]