On Wed, Mar 24, 2004 at 05:55:51PM -0600, Gordon Fecyk wrote:
A> SPF-like proposals also scale well
Something that requires pre-registration of all of the places
I may send
mail from does not scale all that well. Imagine having to preregister
every telephone you might call from.
At least that's what my phone company calls them - effectively a credit card
for making local and long distance phone calls without depositing money.
It's my "registration." But that's more analogous to SMTP AUTH, or SMTP AUTH
over a different port.
"location that blocks use of calling cards except the ones they sell, by
blocking outbound toll-free calls" (yes, they do exist, and are the
calling-card equivalent of hotels that transparently hijack outbound
toll calls to route them over their own preferred LD carrier, for
profit. Until recently, I faced one at work, and there was NO way
around it: cellphones were verboten, and as it's a remote jungle
location, you either jumped through their hoops or did without.
Unfortunately, business needs eliminate the "do without" option.
This is even beginning to happen with cellphones in Japan --
the cellular signal is intercepted and routed through the location's
private cell net instead.)
So yes, both SMTP AUTH and calling cards are solutions to the "I desire
that my outbound traffic take a particular route" problem. But they
aren't a solution to the "I am unable to direct my outbound traffic over
a particular route due to ( sending device limitations | external
restrictions imposed with or without my knowledge )" problem.
The assumption that device limitations are easily overcome, and the
assumption that external restrictions are always known and/or easily
avoided seem to underly your approach. How should a cellphone user
facing a transparent SMTP proxy solve this problem?
Short of completely reconfiguring the MUA, how should an end-user
borrowing a friend's/co-worker's machine or using a public terminal
solve this problem, without resorting to insisting that there be
web-based email available?
The die-hards who just have to be their own MTA can use dynamic DNS to
"pre-register" and "de-register" their locations seamlessly.
Again, I'll hold up the cellphone user as an example of use in which
this is simply not possible without a good deal of effort on behalf of
the cellphone equipment provider and the cell carrier (as the two often
work cooperatively, though some would say antagonistically) to deploy
firmware updates to phones.
Mark C. Langston Sr. Unix SysAdmin
Systems & Network Admin SETI Institute