A natural progression is for Usenet news and electronic mailing lists
to somehow become merged---which they have, in the form of news
gateways. Many mailing lists are set up to "reflect" messages not
only to the readership of the list, but also into a newsgroup.
Likewise, posts to a newsgroup can be sent to the moderator of the
mailing list, or to the entire mailing list. Some examples of this in
action are comp.risks (the Risks Digest) and
comp.dcom.telecom (the Telecom Digest).
This method of propagating mailing list traffic has helped solve the
problem of a single message being delivered to a number of people at
the same site---instead, anyone can just subscribe to the group.
Also, mailing list maintenance is lowered substantially, since the
moderators don't have to be constantly removing and adding users to
and from the list. Instead, the people can read and not read the
newsgroup at their leisure.
from "Dear Emily Postnews" by Brad Templeton
Usenet "Netiquette"
There are many traditions with Usenet, not the least of which is
dubbed netiquette---being polite and considerate of others. If
you follow a few basic guidelines, you, and everyone that reads your
posts, will be much happier in the long run.