Though I wrote the following in a different context,
I'm re-posting since it does speak to the concept
of "free."  Of course you should add the concept
of list-owner/maintainer time.
 
Date:         Sat, 14 Oct 1995 10:18:00 EDT
Reply-To:     Spam Prevention Discussion List <[log in to unmask]>
From:         "Peter M. Weiss +1 814 863 1843" <[log in to unmask]>
Subject:      E-mail is free?   I don't think so
 
E-mail is not "free" to institutions, especially colleges and
universities.  Here are some of the off-the-cuff cost centers
other than what the end-user might pay on a per message/byte basis:
 
1) system, network administrators, postmaster pesonnel time that
   support e-mail e.g., the Domain Name System, Routers, gateways,
   listservs
 
2) the infrastructure circuits that carry the traffic typically T-1 (+)
   that need to be upgraded based on network loading, including the
   network management thereof
 
3) the system and user's time in processing e-mail (reading,
   writing, filing, deleting, searching)
 
4) the system resources in staging/spooling mail such as the
   time spent by SMTP, temp. disk storage (working set), number
   of simultaneous SMTP connections, userid authentications,
   file system utilization
 
5) the backup / disaster recovery resources (time, equipment, media)
 
6) the "opportunity" cost of handling "important mail" since it
   completes at the same level as junk mail both in the user's
   in-box as well as at the network level
 
I'm sure this is not exhaustive and I'm sure you can quibble with
my particular categorizations.  This topic is similar to one
that was found in the Telecom Digest (Usenet comp.dcom.telecom)
about the true cost of "stolen" phone calls by hackers).
 
/Pete Weiss -- Penn State