Distribute is normally invoked by sendmail from an alias entry in /usr/lib/aliases of the form:
list-name: "|/usr/local/lib/distribute list-name users..."
With lists containing many names, which maybe subject to frequent alteration, it is best to store the usernames in a file and specify the path name of the file with the syntax :include:file, i.e.
list-name: "|/usr/local/lib/distribute list-name :include:file"
There should be a second entry in /usr/lib/aliases for the list maintainer. This is the name of the list with "-request" appended. This should be aliased to the person who is responsible for maintaining the distribution list. e.g.
list-name-request: postman-pat
Distribute should be setuid to one of sendmail's trusted users, so that it will set the sender address to that of the list maintainer.