Brightmail says that "6 of the top 10 ISPs" use its spam filtering
solution.  Their website does not provide the details.  Who are these
6 ISPs?

Hi there,

My answer is that BrightMail currently supplies five of the top 10
ISPs: AT&T WorldNet, AT&T Broadband, EarthLink, MSN and Verizon. The
had former top 10 ISP Excite as a customer before they went bust, Juno
once used them and the #11 ISP Comcast is a current customer.

BrightMail's website only mentions four by name:

AT&T WorldNet, EarthLink, MSN, Verizon Online
http://www.brightmail.com/about_us.html

The press release that mentions "6 of the top 10 ISPs" is at
BrightMail's website:
http://www.brightmail.com/pressreleases/043002_radicati.html

To see how the top 10 was determined would require a peek at the
original report - "Anti-Virus, Anti-Spam and Content Filtering Market
Trends, 2002-2006", which can be purchased from the The Radicati Group
for only $2500.00.
http://www.radicati.com/

According to ISP Planet the top 10 ISPs in the USA are currently: 

1 America Online (Dial-Up) 17.5% 
2 MSN (Dial-Up)   5.2% 
3 United Online (Dial-Up) [NetZero + Juno Online]   3.5% 
4 EarthLink (Dial-Up)  3.3% 
5 SBC/Prodigy (SBC &  Prodigy DSL & Dialup) 2.2% 
6 CompuServe (Dial-Up) [AOL Owned]  2.0% 
7 Road Runner (Cable) [AOL Owned]  1.6% 
8 AT&T Broadband (DSL)   0.9% 
9 AT&T WorldNet (Dial-Up) 0.9% 
10 Verizon (DSL)  0.9% 
11 Comcast (Cable)  0.7% 
12 Cox (Cable) 0.7% 
13 Charter (Cable)  0.5% 
14 BellSouth (DSL)  0.5% 
15 PeoplePC (Dial-Up) 0.4%
http://www.isp-planet.com/research/rankings/usa.html

AT&T Broadband Internet has introduced a new e-mail screening feature
to enable customers to filter unwanted e-mail, or spam, that may be
sent to their e-mail accounts. This feature uses Brightmail (TM)
software to filter spam.
http://help.broadband.att.com/faq.jsp?content_id=1744&category_id=77

[Comcast] has contracted with a San Francisco-based company called
Brightmail to develop spam-blocking filters that will lock out the
worst offenders.
http://www.freep.com/money/tech/mwend6_20020506.htm

Juno used Brightmail in 2000, but I couldn't locate any more recent
indications of this.
http://www.internetnews.com/isp-news/article.php/421071

It is quite common for bragging companies to not change their "fact"
when it becomes out-dated. A real world example is when I visited the
world's tallest totem pole in three different locations on Vancouver
Island. The signs were correct when they made them, they just
neglected to change them when a bigger totem pole was erected
elsewhere.


Search strategy:

"top 10" ISP
://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=%22top+10%22+ISP

[ISP name] BrightMail


I trust this answers your question. Feel free to ask for any
clarifications you may require.

Best wishes,
robertskelton-ga

That's the info I needed, thanks!