[Tfug] Comcast to start blocking port 25?

[Angus Scott-Fleming]

This could be a real PITA for many of us.  OTOH some estimates suggest 
that most (80%?) of spam is spread through zombie PCs on on broadband 
connections.  This could help there.

http://news.com.com/2102-1038_3-5230615.html?tag=st.util.print
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Comcast takes hard line against spam
 By Jim Hu
 Staff Writer, CNET News.com
 http://news.com.com/2100-1038-5230615.html
 Story last modified June 10, 2004, 12:56 PM PDT

  Comcast, the nation's largest broadband Internet
  service, this week began selectively blocking a network
  loophole commonly exploited by spammers. 

  The cable giant, whose broadband Internet service has
  more than 5.7 million subscribers, said it will block
  what's known as "port 25" for accounts suspected of
  sending mass amounts of unsolicited e-mail. The company
  will implement blocks based on subscriber accounts with
  the most outbound activity. 

  Port 25 is a gateway that most computers use to send
  e-mail. That's because a technical specification called
  SMTP (Simple Mail Transfer Protocol), which lets people
  send and receive e-mail, operates on the port. 

  "We are singling out spammers on our network and
  blocking port 25," said Mitch Bowling, Comcast's vice
  president of operations. "We don't think it's the right
  approach to blanket port 25. The right approach is to
  seek out people who are spamming our network and
  others." 

  Comcast's port 25 blocks were first noticed in online
  public forums such as Broadbandreports.com. 

  The move comes amid mounting criticism against Comcast
  for not taking enough steps to thwart spam. Some
  measurement companies have highlighted Comcast as the
  greatest source of spam, most of it from subscribers who
  have no idea their computers have been transformed into
  spamming engines. Measurement site SenderBase estimated
  that 665 million e-mails a day come from Comcast
  domains, more than Yahoo and Time Warner Cable's Road
  Runner service combined. 

  In Comcast's defense, the company is not a direct source
  of unsolicited e-mail, but a convenient distribution
  point due to its size and speedy bandwidth. E-mail virus
  writers have targeted Comcast, among other broadband
  Internet service providers, to turn subscriber computers
  into spam "zombies" without their knowledge. 

  One Comcast engineer estimated the daily e-mail flow on
  the company's network at about 800 million messages,
  with only 100 million originating from its servers. The
  remaining 700 million came from zombie computers. 

  "This is a problem faced by many broadband providers,
  because as speeds increase, those broadband connections
  become a low-cost, high-efficiency delivery connection,"
  said Ray Everett-Church, chief privacy officer at
  TurnTide.com and an antispam advocate. 

  Blocking port 25 would prevent computers from sending
  e-mails from any non-Comcast SMTP server. This, in turn,
  would shut down people using Comcast's bandwidth to send
  spam from their own SMTP servers. It would also limit
  PCs acting as spam zombies from connecting to mail
  servers outside Comcast's network. 

  While many spammers use an open port 25 as a workaround,
  there are legitimate uses as well. More technically
  savvy subscribers and small businesses use the open port
  to connect to outside mail servers or to run their own
  SMTP servers. 

  "We have commercial customers that aren't spammers that
  we don't want to impact," Comcast's Bowling said. 

  Comcast is not the first ISP to take this measure. In
  fact, many service providers such as America Online and
  EarthLink have been doing this for many years. Other
  cable ISPs such as Cox Communications also have
  implemented port 25 blocks to fight spam. 

  For general subscribers who use Comcast as their primary
  e-mail account, the changes will go unnoticed, the
  company said. Already, Comcast has noticed a 20 percent
  reduction in spam since the blocks began and a 75
  percent decline in the past two months. 

  Whether this amounts to any significant reductions of
  spam on the Internet at large is unlikely, because there
  are other sources of junk e-mail overseas. But some
  people consider it to be a step in a seemingly hopeless
  war against spam. 

  "I don't care if Comcast customers are infected. I just
  care that the spam stops," wrote one
  BroadbandReports.com reader in the site's message board.
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