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Path: utzoo!watmath!water!watcgl!dmmartindale
From: dmmartindale@watcgl.UUCP (Dave Martindale)
Newsgroups: net.news.group
Subject: Re: mailing lists vs. newsgroups: facts
Message-ID: <2503@watcgl.UUCP>
Date: Thu, 12-Sep-85 10:25:21 EDT
Article-I.D.: watcgl.2503
Posted: Thu Sep 12 10:25:21 1985
Date-Received: Fri, 13-Sep-85 03:16:47 EDT
References: <828@burl.UUCP> <3500005@ccvaxa> <3221@nsc.UUCP>
Organization: U of Waterloo, Ontario
Lines: 34

Chuq's analysis of the breakeven point for mailing lists looks correct
for the case where the mailing list and the mail systems along the way
are set up in the most naive fashion: every member of the list gets a
copy, and intermediate sites get all of those copies passed through them.

In fact, this isn't necessary.  All versions of UNIX that I know of
except 4.1BSD have an "rmail" that can handle multiple recipients.  Thus,
if site A is sending the same message to 10 people via site B, it need
send only *one* copy over the link to site B, and specify 10 recipients.
If site B is similarly clever, it will also send to multiple people at
once wherever possible on its outgoing links.  This sort of clever forwarding
was first set up on watmath in response to the traffic generated by the
women's mailing list.  As far as I know, only sites running sendmail
have an appropriately-clever mailer, but this includes many sites that
handle large amounts of mail traffic.  And it does require that the system
administrator determine which of the connecting sites can handle multiple
recipients and configure sendmail appropriately.  But they should do this
anyway, in order to cut phone costs.  The amount of work involved is certainly
far less than news requires to keep operating.

Also, as Chuq mentions but neglects to account for in his formula, large
mailing lists can have downstream redistribution points consisting of
mail aliases that automatically redistribute mail (this can be done on
many flavours of UNIX) and ordinary people who perform the same function.
This is also used by the women's mailing list.

In the best possible case, every site could have at most one incoming copy
of the mail message that is redistributed to outgoing addresses by one of
the three methods described above.  Then the total number of messages
would be *less* than that generated by news (because of the multiple
connectivity of USENET, sites often receive 2 or more copies of the same
article) on the subnet that the mail is being sent to.  News does benefit
from compression though.  But it seems that a well-planned
mailing list has a breakeven point that is far higher than Chuq suggests.