On Thu, 2 Nov 2000 03:37:46 +0000,
Howard Schwartz <[EMAIL PROTECTED]> wrote:
>
> This is interesting information. Howard (E) - how do you go about
> finding out if a mail transport program uses things like a command
> line argument, a setup file, part of a mail header, or part of a glue
> envelope -- when it sends the from and to lines to an smtp server?
Lots of testing. :-) I have more than one e-mail account and send
myself test messages from one to the other. The best way to see how
an smtp server actually works is to telnet to port 25 and enter an
e-mail by hand. The "I am sitting in Siberia" webpage has an example
of how to do this. The envelope from is the address you put in the
"mail from" command and the envelope to is the address you put in
the "rcpt to" command. These are the addresses that count. (If your
domain is blocked or the server refuses to relay, you won't be able
to proceed any further). The From: and To: headers that you put
after the "data" command are meaningless as far as the smtp server
is concerned.
Once you've seen how smtp works, you can send test messages with
different transport programs, and look at the full headers of the
received messages to determine which addresses are in the envelope
from and envelope to.
> I expect at some isps, the From line is always your email address
> as they know it, for security reasons -- so you can not fake who
> the mail you send out is from, yes?
You'd have to test it, but I don't think that this is normally the
case. Some ISP's may use rewriting rules or add a header to identify
the sender, but even if they don't, they should be able to track you
down from their logs (IP address and timestamp).
Howard E.
Ottawa, Canada
--
DOS TCP/IP * http://www.ncf.ca/~ag221/dosppp.html
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