[exim] Problem: Exim Retry Mails in Mail Queue using Other …

Hello,

I hope some Exim expert could give me some help or direction on this. This
is weird..

Current Setup: My server has 2 IP.

IP #1: 1.2.3.4 (mx1.abc.com)
IP #2: 5.6.7.8 (mx2.abc.com)

I have this line in my exim.conf.

dk_remote_smtp:
driver = smtp
interface = $interface_address
dk_private_key = "/var/cpanel/domain_keys/private/${dk_domain}"
dk_canon = nofws
dk_selector = default

* I am using server with Cpanel.

Situation:

I send some mails to yahoo.com via mx2.abc.com. From my current setup, exim
will bind with IP #2 which is 5.6.7.8 and connect to yahoo. From yahoo point
of view, it is connecting from 5.6.7.8.

Yes, there is no problem about it. Then Yahoo deferred our mails with code
421 or 451. After that happen, we have some mails stuck in the mail queue,
which is very normal also since later exim will pick up these mail for a
retry.

After 1 or 2 hours, I started to send some emails via mx1.abc.com (1.2.3.4),
so as from my setup, exim will bind with ip 1.2.3.4 and connect to yahoo.
>From yahoo point of view, it is connecting from 1.2.3.4 which is correct.
And for mx1.abc.com (1.2.3.4), there's is 0 deferral from yahoo, all went
out smoothly.

Now the problem is, those mails I sent via mx2.abc.com previously which are
stuck in mail queue, now automatically bind itself to ip 1.2.3.4 and send it
out. The mail queue suddenly cleared and become empty. Checking our mails in
yahoo shows that those mail previously sent via mx2 and stucked in mail
queue, now being sent via mx1. Those mails suppose to comes from 5.6.7.8 now
comes from 1.2.3.4.

This is a serious problem as 2 seperate account shouldn't be sending email
using other people's ip. And it only happen when the mail stuck in mail
queue, and at the same time, the other ip start sending smoothly to the same
domain (yahoo.com).


I am not sure if this is default exim setup or it is a bug, please help. But
sending via other people's ip looks like a security breach to me.

Please help.

Alson.