ip third party e-mail

[frankdowling1]

A question :

When I send a e-mail from hotmail it marks the originating address as my ip.
However when an e-mail is sent from other sites the ip is marked with a 3rd party ip from that e-mail service.
In a discussion a network administrator insisted that he could
always determine the originating ip of an e-mail.
Is this accurate ?? :upside

[zaphodiv]

Assuming the network administrator is talking about email that is delivered to a server he controls then he can keep logs of the ip address of the machine which connected to his mail server on port 25 and transfered an email to it.

If somone sends an email via their ISP's smtp server as normal then the ip address the destination mail server sees is the ip of the smtp server that queued the email. If the ISP mail server that delivers an email does not include in the headers the ip of the dialup/adsl/cable user that originated the email then there is nothing the destination server can do to find that out. Except ask the ISP of course, which probably won't work because they will ignore you/require a search warrant/have deleted the logs after a couple of days etc

If a spammer in the USA uses an open proxy server in Korea to send spam to a mail server then the server just sees an incoming connection from Korea. Without logs from the Korean machine (or the NSA ) you can't determine the spammers ip.