Joe Greco wrote: >> On Fri, 18 Dec 2009, Jason Bertoch wrote: >> >>> Do metrics exist on how many current installs still rely on the implicit >>> MX? >>> >> It's very common for email from web servers to be poorly configured such >> that it uses the webserver's hostname as the return path's mail domain. >> > > It is very difficult to measure how many current installs rely on the > implicit MX, as someone else noted. > > On a somewhat different angle of attack: > > Even five years ago, it was considered mildly problematic to deploy a > hostname where the A pointed someplace incapable of receiving mail, > since some "products" (you know who you are) were so poorly written > and still in use that they would connect to the A (or "implicit MX" > if you prefer) even in the presence of MX records. > > Now that another five years have passed, it would be interesting to > see how many antiques are still sending e-mail AND are worth talking > to. I'm guessing not many. > > That suggests that it might well be fine to point A at something that > is not capable of receiving SMTP, as long as you have MX records. An > arrangement that should always have been practical, of course. > > Is anyone actually doing this? > > ... JG >
I'd think this more than common - the A record for the domain quite often is set to point to the same IP as the www. A record where that server isn't running an smtp service. We've certainly got clients who do this, and haven't ever reported it causing problems = one example :- banquo>host -t A www.thehut.com www.thehut.com has address 89.234.46.152 banquo>host -t A thehut.com thehut.com has address 89.234.46.152 banquo>host -t MX thehut.com thehut.com mail is handled by 3 mail.thehutgroup.com. banquo>host -t A mail.thehutgroup.com. mail.thehutgroup.com has address 217.158.230.4 Regards Pete
