How many legitimate SMTP senders?

[Matthias Leisi]

dnswl.org is currently approaching 50'000 individual IP/CIDR entries.
For a more realistic estimate about the number of legitimate SMTP
senders, we need to make a couple of adjustments:

* subtract some legacy ranges in our DB which need to be phased out
* add the import queue of "IP addresses to potentially include" [1]

Considering this, we arrive at a number of roughly 100'000 legitimate
SMTP senders (individual IP addresses) on todays' Internet, legitimate
being loosely defined as "speaks proper SMTP and has substantially more
ham than spam".

Does this guesstimate match with yours? What is a meaningful error range
- +/- 20%? Is it overall plausible? What would you base your estimate on?

-- Matthias

[1] IPs which have been seen used as SMTP senders, not listed on a
selection of blacklists, and has valid PTR

--
Comments posted to news.admin.net-abuse.blocklisting
are solely the responsibility of their author. Please
read the news.admin.net-abuse.blocklisting FAQ at
http://www.blocklisting.com/faq.html before posting.