Re: SMTP blocked between ISPs

[Mark Handley <M.Handley@cs.ucl.ac.uk>]

>What worries me is that this blocking of port 25 is going _against_ the 
>path which I want to see, that we have no relay in the world. Blocking 
>port 25 _increases_ the amount of relays.

Blocking port 25 is only part of the story.  

There's also blackhole lists like the MAPS Dial-up User List:
   http://mail-abuse.org/dul/
I've hit this dialing up from a free ISP account in some random place.

Also there's the reverse-MX proposal:
  http://www.ietf.org/internet-drafts/draft-danisch-dns-rr-smtp-02.txt

All of these are pushing further into a world where you'll be required
to send though your ISP's outgoing mail server.  

I suspect this progression is inevitable, unless some better
alternative anti-spam mechanism is standardized and deployed in the
near future.

Cheers,
	Mark