Re: SMTP service (was: Reply blocks and tagging protection: a third variant)

[Roger Dingledine <arma@mit.edu>]

On Wed, Apr 10, 2002 at 12:30:19PM -0400, George Danezis wrote:
> What about the following: The mix sends a notification by email (or 
> other) that a message is waiting, and the client can then choose to go and 
> download it.

This raises two issues. (None of this is ever as easy as it should be,
alas.)

First off, it increases liability for the exit nodes: now they are
actually storing potentially-bad material. I proposed this idea to
Robyn Wagner at FC02 (she's a remop and is just finishing law school),
and she was really convinced that there was a serious legal difference
between just passing on encrypted mail and actually storing mail for
people. Whether we could make it into a grey area by encrypting the
stored mail with a key which we include in the notification and then
forget, I don't know. It would be tricky though.

Secondly, there's the issue of deniability of interest to receive the
mail. This is very similar to the case of Lamont v. Postmaster General,
US Supreme Court 1965. The idea there was that Customs officials would
examine mail coming into the US, and if they deemed it to be communist
propaganda they would instead send a little notification saying "please
let us know if you want us to send you this communist propaganda". (See
page 30 of http://freehaven.net/doc/freehaven10.ps for more details.)

If I'm amnesty international then it's fine to admit that I like getting
mail from the mix-net. But if I'm some random dissident, I may still want
the deniability of "huh? i dunno, this thing just keeps sending me junk."

I think a good interim answer here is for users to make use of free pop3
servers that are online most of the time, eg hotmail.

--Roger