In message <20050919212711.GA17693@???>, Wakko Warner
<wakko@???> writes
>>The idea
>> being that email from paypal.com will come from paypay servers somewhere
>> in received.
>
>What's so hard about this???
We don't currently have a universally deployed mechanism for indicating
where email comes from -- so you are stuck a mixture of experimental
protocols and heuristics
Significant complications arise with email forwarding especially when
you consider that the system that passed you email might be wishing to
mislead you into the veracity of the information it provides...
>mx custserv.paypal.com.
>> custserv.paypal.com does not exist, try again
>mx accounting.paypal.com.
>> accounting.paypal.com does not exist, try again
>mx paypal.com.
>> paypal.com MX 10 smtp1.sc5.paypal.com
>> paypal.com MX 10 smtp2.nix.paypal.com
>> paypal.com MX 10 smtp1.nix.paypal.com
>mx com.
>> com MX record currently not present
>
>Just strip the subdomain off until you get an MX. How difficult could that
>be??? You can do this with embedded perl and it would be quite easy to do.
The MX records tells you something about where email is delivered to
when sent from the Internet. In some cases (mainly smaller sites) it may
tell you something about where email comes from; but of course it can
never tell you about private arrangements for outgoing email :(
So it's a heuristic, but rather a flawed one :(
>If you're wondering about say demon.co.uk:
>mx demon.co.uk.
>> demon.co.uk MX 5 lon1-hub-internal.mail.demon.net
>> demon.co.uk MX 5 anchor-hub-internal.mail.demon.net
>mx co.uk.
>> co.uk MX record currently not present
>mx uk.
>> uk MX record currently not present
Start by looking up, for example, happyday.demon.co.uk (where this email
actually came from) to see how confusing this immediately starts to
become ...
- --
richard Richard Clayton
They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety. Benjamin Franklin
