Author: Phillip Carroll Date: To: exim-users Subject: Re: [exim] Changing email headers to reflect server IP when they
pass through Exim
On rereading what I wrote earlier, I realize I didn't adequately explain
the process of emailing via SSH tunnel.
The specific SSH client I use in Windows supports the ability to forward
arbitrary listening ports on the client computer to arbitrary
destination ports on the SSH connected server.
I use ThunderBird on my desktop as both an IMAP client, and SMTP client.
ThunderBird is configured to use arbitrary ports on IP 127.0.0.1.
The SSH client is configured to listen for these ports and forward them
to the IMAP and SMTP ports on localhost at the connected SSH server.
(Exim is the smtp server software, and Dovecot the IMAP server software.)
Also: Technically, I HAVE used a mobile device for an SSH tunnel,
specifically an Android cell phone. However, the phone had no SSH
software itself. It was simply a signal relay device. The phone was
connected via USB to my Windows 7 notebook that was running the SSH
client described above, while tethered to the Verizon 3G network on the
other side. Same TBird hookup for sending and receiving email as I am
doing right now.
An actual SSH client app on the cell (for greater email mobility) would
need to support port forwarding of the type described (or something
similar) to originate emails on the cell.
On 4/21/2015 9:39 AM, Phillip Carroll wrote: > On 4/17/2015 11:15 AM, James Worix wrote:
>> we have an issue with mobile devices that use third party email clients
>> to send and receive emails. The problem being that when they are in the
>> field using Verizon LTE or similar that their dynamic ips are
>> automatically blacklisted in most major DNS lists. I only really have 2
>> options.
>>
>> 1. Everyone buys a clean static ip (expensive)
>> 2. Rewrite the headers of the email to reflect the server's ip address
>> (free)
>
> Actually, you are overlooking a third option:
>
> This post is being sent from my desktop via a Comcast Cable IP, which
> you will find nowhere in the header. Instead, you will see that it
> originates on the exim server itself, located about 800 miles away.
>
> I send and receive all email using an SSH tunnel between my desktop and
> the server.
>
> Although I have never done this with mobile devices, a quick web search
> will show you that SSH is readily available for a variety of mobile
> devices.
>
>
