I was thinking of something like this (sketchy outline, any use of
"spam" is simply short-hand for "Insert Better Term"):
Spam (definition) currently comprises over 90% (cite) of email
traffic.
The enabling technology for the vast majority of spam are botnets
(description.)
Botnets are particularly problematic because:
a) They allow spammers to command far more resources for sending
spam than the underlying business activity could ever fund; the
resources used are all stolen. Literally hundreds of millions of
copies of a message can be sent out for little or no cost to the
spammer.
b) They allow for address mobility; spam sources can shift between
thousands of purloined computers rapidly thus defeating
identification of the source of the spam for the purpose of blocking
or, where warranted, criminal investigation.
c) They are a fundamentally criminal enterprise relying on the
injection and exploitation of malicious software into victim
computers.