MTA (exim/sendmail) Aliases
If a system administrator is willing to take on the task of maintaining list membership this can be done quickly using a sendmail aliases:
# Alias for distribution list, members specified here:
staff:wnj,mosher,sam,ecc,mckusick,sklower,olson,rwh@ernie
A sysop may also allow aliases that point to lists that are managed by individual users:
# Alias for distribution list, members specified elsewhere:
mylist: :include:/usr/home/user/my-list
While both of these are quick to set up, they require hand maintenance by the owner.