> On Nov 13, 2017, at 9:05 AM, Federico Santandrea > <federico.santand...@diennea.com> wrote: > > Hello, > > I am working on a rough draft for a protocol meant to facilitate exchange of > deliverability information among ESPs and mailbox providers. > > This arose from the observation that providers who choose to publish a > description of what they consider to be an acceptable mail flow, do this each > in their own way (FAQs, postmaster pages, helpdesks) and one has to keep > track of everything everywhere. > > I thought I could ask here for relevant opinions before getting too deep into > it, as I don't want to elaborate on what could be a known or unknown bad > idea; this seemed a suitable initial discussion venue to me. > > The draft text can be found at: > https://www.ietf.org/id/draft-santandrea-mail-limits-00.txt > > Would this fill anyone else's needs and benefit the community? > Any feedback is appreciated.
The difficult issue here is people+policies+politics, not a communication protocol. ISPs usually don't have particularly consistently defined delivery constraints. Constraints are likely to vary (wildly! by many orders of magnitude!) depending on the history of the smtp peer, both very recent and over multiple weeks. If the ISP were to publish the constraints that were applicable to SMTP from strangers they'd often be low enough that many senders wouldn't be able to comply with them while still delivering the mail they need to deliver, so I can't picture a choice of values to publish that would be of value to (or could be followed by) most senders. Those dynamic policies vary from provider to provider, and aren't implemented consistently enough that you can necessarily sum them up with a few common variables. And I would bet that at many ISPs you couldn't find someone who could tell you what their constraints are, as they're tweaked in an ad-hoc way using knobs that don't directly map on to the variables you're looking for. And even if you could on Monday, that doesn't mean it'd be the same by Wednesday. Those providers that do publish constraints often aren't publishing the real constraints - they're publishing a baseline of "if you're doing more than this, and you're getting rejections or deferrals, don't bother contacting us". That's fine for customer support pages, but not something you'd want to feed into sending automation. Publishing those in machine-readable form risks people putting too much trust in them. (If this proposal were coming out of a group of major ISPs or a few of the larger inbound mail appliance or service providers as "this is something we want to do" I'd consider it differently than it coming from the high volume email deployer side of things. There's a long history of bulk mail senders going "just tell us exactly what we need to do so you'll deliver our email, and we'll do it!" and it's not something that ever really leads anywhere.) Cheers, Steve _______________________________________________ mailop mailing list mailop@mailop.org https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop
