Re: [exim] sending to only one domain per connection

On 27 Jun 2012, at 15:55, Graeme Fowler wrote:
> On Tue, 2012-06-26 at 15:59 +0300, Marius Stan wrote:
>> I guess you're already aware of the new limits imposed by google-hosted mail servers:
>> "Multiple destination domains per transaction is unsupported"
>> This caused a LOT of bounces lately and I still haven't figured out what to do...
>>
>> Any ideas on some transport/driver magic ?
>
> No, but I don't see that we need to. This only seems to be active on
> servers under the name aspmx.l.google.com; in the same session Exim
> falls back to the other MX records for the domain(s) in question and
> send the remaining messages down that connection instead.
>
> Although this is not strictly RFC compliant behaviour I have not seen it
> actually cause any problems whatsoever - perhaps a one or two second
> delay in delivery to Google, that's all.
>
> I think I'll ask our work Google Apps contacts about it, see what they
> say.
>
> Graeme


Those are interesting observations. I guess if there's a quick retry that succeeds, then there's no problem, but the OP reported bounces.

hosted domains have this set of MX records:
eiloart.com mail is handled by 30 alt2.aspmx.l.google.com.
eiloart.com mail is handled by 40 aspmx2.googlemail.com.
eiloart.com mail is handled by 50 aspmx3.googlemail.com.
eiloart.com mail is handled by 10 aspmx.l.google.com.
eiloart.com mail is handled by 20 alt1.aspmx.l.google.com.

Each of those domains resolves to a single IP address. So, the fourth and fifth priority servers are picking up the pieces.

I've also seen the error message on the primary MX host for gmail.com domains. This smells like an experiment to me. It's a recent development. I first see the error message on 3 May this year. Though, I guess it could be the error message that changed that day.

If they're not doing it on all their servers, then I guess they can't be offering domain specific rejection settings. Not yet, anyway.

I guess SMTP over IPv6 would fix this for them.

--
Ian Eiloart
Postmaster, University of Sussex
+44 (0) 1273 87-3148