Digests

[utzoo!decvax!ucbvax!unix-wizards]

>From lauren at UCLA-Security Sat Sep 26 11:19:24 1981
The primary reason for digestifying a list is not to censor messages or 
even to control content, but simply to prevent the entire "system" from
breaking down when message traffic starts getting very high.

There are two primary forms of "breakdown":

1) Many users, who often have much to contribute to the dicussion, find
   themselves being bombarded with separate messages throughout the day,
   which can be very distracting.  These people tend to drop off the
   list, and the loss of their input can be expensive to the list at large.

2) The networks and supporting computers begin to have problems when
   load starts to get high.  It is much more costly (in terms of machine
   time) to deliver lots of separate messages to a given site than an
   occasional big message.  As lists begin to get very large (Unix-Wizards
   may not have reached this point yet) this issue gets very important.
   This problem affects not only the machine distributing the digest, but
   every machine which receives the digest.  It is not unknown for a site
   administrator to "disallow" the reception of certain lists when load
   starts to become a problem (from lots of separate messages).

Digests have some very good features, one of which is that similar questions
and comments can be clumped together in an orderly fashion -- this has
served well in most other digests, including WORK-S, which started out
in direct distribution mode.

Digests have some bad features, the most notable is that it is more
difficult to use automatic reply mechanisms (on most sites) to reply
to a particlar digest message.  There is work being done in this area,
and in fact Roger Duffey (net mailing list guru supreme) and I discussed
some of these problems when I was in Boston a few days ago.  Perhaps
Roger could comment further on the issues of digests as they relate
to growing mailing lists.

--Lauren--