--On 11 July 2007 09:29:44 +0100 Philip Hazel <ph10@???> wrote:
> On Tue, 10 Jul 2007, Marc Perkel wrote:
>
>> OK - if the second message were from a different IP then it would also
>> have to try twice.
>
> Well, there are certain configurations where it won't. At least, not in
> the order that you require.
>
>> Tell me about this virtual server feature with shared data. What feature
>> is that?
>
> The feature is the ability to select which IP you send from when your
> box has more than one. The Exim option is the "interface" option in the
> smtp transport, and also the helo_data option, which allows you to
> change HELO data.
There's another configuration that might lead to a similar problem.
We have four physical hosts, with different IP addresses, but serving email
for the same set of domains.
Currently, the hosts don't share their retry databases, but we're
considering doing that.
Even though they don't share retry databases, we have an IP failover
mechanism which can move an IP address from one host to another in less
than a second. In that case, the IP address that moves effectively picks up
the retry hints from the new server. Now, there are conceivable
configurations that would fall foul of Marc's scheme, where the virtual
server that's moved apparently tries to go straight to his secondary.
Admittedly, failover doesn't happen often, so this event would be rare.
--
Ian Eiloart
IT Services, University of Sussex
x3148
