On Mon, Mar 03, 2003 at 08:07:45AM -0500, David F. Skoll wrote:
Well, couldn't you relay through your ISP's SMTP server, and put that
server as your RMX record? This isn't perfect -- it means all of your
ISP's customers could spoof mail from your domain, but it's better than
nothing.
Well, it would be the responsibility of the ISP's SMTP server to
somehow check the authenticity of the mail. Some ISP's have SMTP
servers which always know which customer an IP address is currently
assigned to. So your customer might restrict usage of your domain
as a sender address with any mechanism - password authentication,
single sign-on, your IP address. But that's a black box from an
outside point of view.
Your RMX records could state that your mail comes from this
certain SMTP server only. How you ensure authenticity within this
server, that's your private business and beyond the scope of the
draft. But that's a design criteria. In contrast to PKI, I want
to leave it the domain owner's private business whether and how
intra-domain-authenticity is checked.
Nevertheless, I do not think RMX records will fly in practice.
There are often legitimate reasons for relaying through other SMTP
servers, such as when you're on the road and using an ISP's global
roaming service.
Yes, I often heard that argument. But
- What's the technical difference between you on the road and
and Spammer? How will you distinguish your mail from a spammers
mail abusing your domain?
- Even when I'm on the road and using a foreign ISP on the other
side of the world, I always drop my email to the very same relay
machine, simply because thats easier. My notebook doesn't need to
bother with DNS queries and temporarily unavailable peers.
I drop all my outgoing mail to central host, and this host is
doing the job.
And that's not too much to ask for, because you need a central
relay for receiving your mail anyway. How do you receive mail when
you're on the road? You need some service provider who receives the
message for you and allows you to download it. It's not a bad idea
to do the very same for sending e-mail in reverse direction.
If you receive e-mail through a central relay, so what's the
problem with sending e-mail the very same way?
regards
Hadmut
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