[unisog] Any Canadian Universities on here ?

Andy Feldt feldt at nhn.ou.edu
Wed May 4 15:35:41 GMT 2005

Sylvain Robitaille wrote:

> On Wed, 4 May 2005, Pete Hickey wrote:
> > ... it SEEMS like rogers is starting to/thinking of blocking port 25.
> In my opinion, it's about time that they do.  Most of the spam, and a good
> percentage of the email-borne malware we receive arrives from unblocked
> "client" systems at large ISPs.  Rogers are hardly the most represented
> in my analyses (read "periodic grepping through logs") of the problem,
> but they do show up as more than a "blip".
> When ISPs block outbound port 25 as a general rule, it will become much
> easier for them to control spam and viruses from their clients.
> > We end up supporting their mail client configuration, so that they
> > can use their university addreses from home.
> I don't understand: they can use whatever address they want, so long as
> they use their ISP's SMTP server to send mail through, no?  Certainly
> that's not been a problem for us ...

There is a broader issue here.  Ultimately, it would seem that the
best solution is for a user to authenticate themselves to, and
send e-mail via, the mail server associated with their domain.  This
allows the domain to utilize a scheme like SPF so that receivers of
e-mail can choose to reject e-mails stating they are from a user at
that domain but have not been sent by an authorized mail server.
Widespread adoption of this would make a significant impact on
current spam distribution via zombies.

We are moving toward that goal and have run into ISPs which block
port 25.  Fortunately, we can use an alternate port to achieve the
same goal (at least so far! - it would be problematic if ISPs began
a grander scale of port blocking).

Andy Feldt
Senior System Support Programmer
Affiliate Assistant Professor
Department of Physics and Astronomy
The University of Oklahoma

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