On 25/May/10 03:55, Steve Atkins wrote: > On May 24, 2010, at 6:38 PM, John Levine wrote: > >>>> Refusing signups from those domains is probably a bit extreme, though. >>> >>> What about a warning at signup time if a "discardable" ADSP record is >>> found for the registrant's domain? >> >> That doesn't help. In the IETF's scenario, domain A sent mail which >> was marked discardable to the list, and recipients at domain B were >> rejecting it and the people at B got bounced off the list. I'd have >> to squint awfully hard to come up with an argument that it is wrong to >> reject unsigned discardable mail at SMTP time. > > I think that Murray was suggesting that in addition to rejecting all > mail from domain A it would be polite to also warn anyone from > domain A who subscribes to the list that their mail would be > rejected (which seems good UX design to me).
That warning is an /alternative/ to refusing signups. The BCP distinguishes between participating and non-participating MLMs, and that warning belongs to the former kind. I'd expect a participating MLM has also fixed the double-footer problem, while most lists have no problems with double subject-tags. Hence, the warning may merely recall that posts from the discardable address will be rejected unless they include the correct footer, and the subject-tag appears exactly once, the latter especially for new posts. (Notice that such practice is may also help to avoid light-minded posts.) We cannot suggest anything to DKIM-unaware MLMs. Hence, the "refuse signups" option, that would apply in this case, has to be put through by subscribers themselves. >> Since ADSP causes problems for innocent bystanders, I think it's >> reasonable to decline A's mail in the first place. This is doubly >> true since the ADSP RFC rather specifically says that you shouldn't >> mark a domain discardable if its users send mail to lists. > > It causes no problems at all to innocent bystanders in that case - the > recipient at domain B is a willing participant who has chosen both > to pay attention to ADSP and to respond to it by rejecting, rather than > discarding, mails labeled "discardable". That user will probably contact postmas...@b and ask for the relevant list to be whitelisted. If a list's operators seek such explicit whitelisting at their subscribers' MXes, then they might want to leverage ADSP that way. BTW, is "discard" exactly synonym with "drop"? I'd recommend dropping mail only in cases of negligibly low FP rates _and_ high risk, e.g. viruses. Deliver-as-junk is used as a makeshift, and I tend to associate "discardable" with such behavior. Is that what RFC 5617 means by it? _______________________________________________ NOTE WELL: This list operates according to http://mipassoc.org/dkim/ietf-list-rules.html
