[115394] in North American Network Operators' Group
Re: Is your ISP blocking outgoing port 25?
daemon@ATHENA.MIT.EDU (Charles Wyble)
Thu Jun 18 15:54:11 2009
Date: Thu, 18 Jun 2009 12:52:45 -0700
From: Charles Wyble <charles@thewybles.com>
To: nanog@nanog.org
In-Reply-To: <01aa01c9f04c$1d0a8820$e76ed48d@zhiyunpc>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Zhiyun Qian wrote:
> It has been long heard that many ISPs block outgoing port 25 for the purpose
> of reducing spam originated from their network.
>
Well blocking or redirecting to there servers, which have an
undocumented filtering policy. All one needs to do in order to bypass
that is use a vpn. Something lightweight like n2n could be used by the
bot herders of the world.
I worked for a company that sent out several hundred thousand messages
per day (an online card/invitations company). We ran spam assassian on
our outbound farm, to prevent folks from using us to send spam. I
presume the large service providers do the same.
>
> AT&T is the major one that I know of that is still enforcing this policy.
> But they said they can unblock port 25 upon request. I am not sure how easy
> it is.
It's trivial. A web form. You get the link when you try to send mail to
port 25 anywhere else. At least with Yahoo/SBC dsl.
I got the business class DSL from AT&T and no such nonsense exists.
