On 2016-12-16 17:58:26 +0000, Joe wrote: > It is therefore an important matter that the email admin ensures that > the PTR record *always* resolves to a hostname which resolves back, > which can if necessary be achieved by creating a fictitious A record for > just this purpose. It is not necessary for this hostname to match either > HELO or domain MX, though it's worth doing if that isn't difficult.
But you need to hope that the nameserver is compliant and in particular, won't truncate the list of IP addresses as with: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=834098 > This check used to be pretty much a guarantee of a business IP address, > but unfortunately many home ISP accounts now have complementary A-PTR > records, making spam detection much harder. Their users may need to send mail after all. -- Vincent Lefèvre <vinc...@vinc17.net> - Web: <https://www.vinc17.net/> 100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/> Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)
