Re: Lenny/exim4: how to set helo for outgoing SMTP

[Kilian <kil@gnu.ch>]

randall wrote:
> Kilian wrote:
>>
>> I have a firewall with a public IP and a PTR record for that IP. There
>> are several hosts behind the firewall with private IP addresses. 
> 
> i have the same, but i have setup one of them to relay the mails for all
> of them, not sure about your setup but this would simplify your problem
> a lot.

Hehe, this is exactly what I had before, but one server sends out a lot
of periodic mailings (legitimate! beware ;-) and it simply overloaded
the smarthost, which is the main mailserver. So the mailing had an
impact on the users on the main mailserver, which was not acceptable, so
I decided the server on which the mailing script runs should send out
the mails directly.

[...]
>> Now to the receiver SMTP, my host appears as the firewall, so IMHO, it
>> must identify itself with the hostname set in the DNS for the firewall.
> 
> correct, but note that that it has to identify with the hostname of your
> "reverse" DNS, it took me a while before i understood this concept myself.

Yes, that I am aware of and that is what I am trying to accomplish.

>>> if both HELO and the PTR record say mail.server.com there is no problem,
>>> whatever the domain of the send mail might be.
>>>     
>> Exactly, and herein lies my problem...
> 
> maybe i mist something, but what does is it precisely use as its
> hostname at this very moment?

In the HELO sequence, it's using the hostname from the DNS inside the
DMZ which is of course not identical to the PTR-RR of the firewall on
the internet...

	-- Kilian