On 4 Jan 2018, at 11:47, Bill Cole <sausers-0150...@billmail.scconsult.com> wrote: > On 3 Jan 2018, at 15:42, @lbutlr wrote: >> There is no requirement that the right side be globally unique, just that >> the entire message ID is globally unique. > > Right. And any software that can use localhost (or any other unqualified name > whose meaning is contextually variable) as the right hand side is likely to > be doing so on multiple machines that don't know about each other and so > generally cannot know that they are not generating duplicate MIDs.
Sure, but depending on how the MID is generated it can certainly be statistically unique. As I said earlier, it only takes 256 bits to get an ID within spitting distance of the number of atoms in the universe. Should be unique enough. > The reason for the RHS=FQDN tradition is to establish a namespace for each > domain whereby global uniqueness can be guaranteed deterministically. OH, I absolutely agree that using the domain for the RHS is a great idea, and there's really no reason not to. But there are other ways. >>> An additional ~1% has a MID header with either no dots or no '@'. >> >> Dots are irrelevant, but the way I read the RFC, ‘@‘ is required. > > See the message I was responding too, which asked about the feasibility of > enforcing a "valid domain" rule. For that, dots are absolutely relevant. My > point, in short, is that doing so may result in 2 orders of magnitude more > rejection of wanted mail than most sites would deem tolerable. Yep. Requiring MIDs to conform to out-of-spec requirements is sure to cause trouble. -- You and me Sunday driving Not arriving
