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

[Peter]

On Mon, 17 Apr 2006, Lennart Sorensen wrote:

> 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.

But that would be a 'properly' (ahem) configured ISP. We are talking 
about the _other_ ones. Plus, you said, yourself, what is wrong with 
that. Obviously the blocking of outgoing 25 won't pull in many customers 
at a colocated server farm or any ISP interested in supplying power 
users in general.

>> 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.

Yes, you can. The case of a 'bsofh' ISP is not what I was considering. 
Most spam origins aren't like that at all. They are _too_ lax.

Peter
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