Re: [nznog] Xtra and SPF

Hi Glen. Sorry for top posting, not replying to anything in particular in this message, but the thread in general. I had intended to send this a while back when the thread was active but forgot, and, now the weird-ass late message from Jeremy brought it back to my attention. Anyway, email forwarding can mean several different things, I’m not sure if the terminology is well defined, but effective there are 3 main ways you can do it: 1) Rewrite envelope recipient 2) Rewrite envelope recipient and sender 3) Rewrite envelope recipient and sender, and header To (and optionally From) It is well understood that SPF does not work well with (1). I’m surprised that this is the first time you have encountered this - perhaps you have other customers who have hit it silently. My recommendation if you’re building a mail product with the option for forwarding, is to: 1) Rewrite envelope recipient (obviously) 2) Rewrite envelope sender to the original envelop recipient (i.e. your customer’s email address in your system) with an additional tag so it is clear that email to that address (bounces) are not to be forwarded. 3) Catch bounces back from the destination server, and act on them in some way. Perhaps you temporarily disable forwarding, and queue mail up, then re-try it from time to time. Perhaps you have a way to alert the customer through some alternative email address or other means. Make sure you don’t re-forward those bounces to your customer - this is what the tag in (2) is for.

On 8/02/2017, at 12:46 PM, Glen Eustace wrote:

Hi,

We have started receiving complaints from several of our customers for whom we are the MX for their domain. Some addresses in the domain are delivered locally, some are relayed to other mailboxes e.g. gmail and xtra.

It seems that there are folks who still believe that SPF is a good thing and have ‘-all’ on their record. Xtra it would appear is now enforcing the rejection on email we relay to them. We are placed in an awkward position. Our customer wants us to fix something that we are not really able to. The SPF policy belongs to the sender and Xtra are doing the rejection.

I have come across another add on technology for postfix called SRS for rewriting senders but that seems to be broken from all accounts as well.

Is anyone else having these sort of issues, is there something I should be doing in the ‘relay’ process that will prevent the rejections I’d love to hear.

Glen -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Glen Eustace, GodZone Internet Services, a division of AGRE Enterprises Ltd., P.O. Box 8020, Palmerston North, New Zealand 4446 Ph +64 6 357 8168, Mob +64 27 542 4015

“Specialising in providing low-cost professional Internet Services since 1997"

_______________________________________________ NZNOG mailing list NZNOG(a)list.waikato.ac.nz https://list.waikato.ac.nz/mailman/listinfo/nznog