Re: [exim] $sender_host_address

On 03/11/14 10:14, Phillip Carroll wrote:
> The chapter on variables says $Sender_host_address is null for local
> host. If the message arrives from 0.0.0.0 $sender_host_address contains
> 0.0.0.0. Likewise, 127.0.0.1, etc..

Here's the documentation on that variable

> $sender_host_address
> When a message is received from a remote host, this variable contains
> that host’s IP address. For locally submitted messages, it is empty.

Notice that it says "locally submitted" and not "local host" as these
are quite different things.

Locally submitted means that exim has been called in "sendmail" mode on
the command line with the email submitted on standard input. This is the
case where $sender_host_address will be empty.

In terms of networks, when any server connects over TCP it is considered
a "remote host" and this is when the $sender_host_address will be filled
the remote ip address of the TCP connection. That can be a server in
China, or it can be a local website submitting to 127.0.0.1.

The documentation could be adjust slightly to not mention "remote host"
as while it is completely true, it is confusing if not familiar with TCP
connections. "When a message is receive via a TCP connection ..." - I am
not a wordsmith.

Ted.