Comcast blocking port 25? (not what you think)

[bscott at ntisys.com]

On Mon, 10 May 2004, at 10:53am, travis at scootz.net wrote:
>>> Yah, that's what I'm going to have to do.. BLAH.. stupid comcast.
>>  
>>   Get used to it.  More and more ISPs are adding this.  And I cannot say I
>> entirely disagree with the policy.
> 
> Why?

  Mail abuse.  A great deal of spam and other mail abuse comes from
computers on consumer feeds that are incorrectly configured as a mail relay
(don't ask me how, but it happens more often then you would think), or have
been compromised by some kind of malware and are being used as same.  At the
same time, SMTP was designed to move mail between static, well-connected
systems.  Hosts on dynamic, consumer feeds do not meet that definition.  It
makes more sense for such hosts to submit mail to a smart host which can do
the job right.

  Of course, then you have to deal with the fact that a great many MUAs are
incapable of doing anything themselves, and need to be able to submit mail
to an SMTP-like listener.  That is why the concept of an MSA (Mail
Submission Agent) was created.  The idea is to separate mail submission from
mail exchange.

-- 
Ben Scott <bscott at ntisys.com>
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