Re: [exim] Exim4 (x2) and mail relay unusual behaviour

Hi Edward,

On Mon, 18 Apr 2011, Edward Cox wrote:

> Both mail and mail2 have the exim configuration files (mail uses
> update-exim4.conf.conf and the variables fill in the DEBCONF template.
> mail2 has a 'configure' file in /usr/local/etc/exim)
>
> mail2 has a domainlist relay_to_domains that includes a domain name we
> host myotherdomain.com.au mail does not have this entry in
> dc_relay_domains field.
>
> Yet, and here's the twist, until recently we were successfully receiving
> mail for fred@??? - despite there being no domain relay
> allow type rule in exim4 on the primary mail server. Just on the
> secondary mail server.
>
> Does that all make sense? Hope so. Would really like to know what's
> happening here.

Because relaying is allowed, mail2 will accept any emails that it receives
for myotherdomain.com.au and forward them directly to their MX, bypassing
your primary server.

So some email for this domain will be received, and some will bounce,
depending on which MX random clients out on the Internet end up talking
to.

This should still work if you end up talking to mail2 rather than mail.
You could test it with swaks or telnet.

Cheers, Chris.