Re: Emacs 21.2, smtpmail and vm

[Simon Josefsson]

"Stefan Monnier <foo@acm.com>" <monnier+gnu.emacs.help/news/@flint.cs.yale.edu> 
writes:

>>> Could anybody give me the skinny about "why would an ISP require SMTP AUTH"?
>> Isn't the answer the same as why authentication is required it all, in
>> any protocol?
>
> I'd only buy that if its use were systematic, which it obviously isn't.

It takes time for people to realize that authentication is required.
Few of the old Internet protocols included authentication from the
start.

>> If you are thinking that ISPs should use IP based ACLs to allow
>> relaying for their customers, it's not going to work with todays
>> computer habits (people travel with their laptop and expect the mail
>> server to continue to work).
>
> By "laptop" you mean "those things with small screens and shallow
> keyboards"?

Yes.

> I must admit I don't know enough of how those things work when you
> try to use the Internet away from home (or office).  But it seems
> you'll need to get your IP from some ISP which is responsible for
> routing to/from your IP and which has a mail server which you should
> be able to use (like you probably use their DNS server).  And given
> such a context, it seems that IP-based authentication would be
> pretty safe for SMTP.

Ordinary users doesn't know about IP addresses and forgets about the
SMTP server after configuring it once.  One might think that DHCP
could set the SMTP server address as it does the DNS server address,
but there are practical problems: You cannot easily abuse a DNS server
as a client, but you can very easily abuse a SMTP server as a client
(spam).  Just because people with their laptops get their IP from an
ISP doesn't mean that the ISP know whom that person is, or know how to
sue her when she sends spam through their network.  If people route
their stuff via their home, it is not the ISPs problem any more.