Will certified e-mail stop spam? (was: unsubscribing... etc)

[Lennart Sorensen]

On Mon, Apr 17, 2006 at 09:16:02PM +0300, Peter wrote:
> True. But port 25 incoming has nothing to do with spam sending. Current 
> botnets send spam by forging packets or so it seems.

Sure it does.  It has a lot to do with sending spam.  If your ISP blocks
outgoing port 25, then you can't make a connection to any mailserver
anywhere, so you can't send any email at all.  The only place you can
send email is through the ISP email server, and then they have a log of
who did it and when.  It is probably the single most effective thing an
ISP can do, much as I personally hate not being able to do my own email
server.

> Port 25 has nothing to do with it on the sending side. The packets are 
> forged, header, origin port and everything.

You can't forge the destination, which is port 25 on some mail server.
It has everything to do with sending.  You have to connect to deliver.

> About your idea that Unix machines send the majority of spam, I do not 
> agree. The largest spam-originating countries are well known, USA is one 
> of them, and due to the low penetration of Linux it is logical that the 
> majority of spam comes from something else. The mahority of 
> installations are Windows machines. Spam origins vary widely enough to 
> eliminate the idea that they come from a few machines.

Certainly windows machines with malware on them on a high speed
permanently on connection is a major source of spam.  It is too bad a
lot of ISPs do not block port 25 outgoing, although even if they do
email can still be sent through the mail server of the isp if the
malware is clever enough to do that.  If the ISP then doesn't respond to
spam complaints, well then there isn't much you can do.  The ISP does
have to take some interest in preventing machines on their network from
being a source of spam.

Len Sorensen
--
The Toronto Linux Users Group.      Meetings: http://tlug.ss.org
TLUG requests: Linux topics, No HTML, wrap text below 80 columns
How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml