On 01 Aug 2016, at 11:02, Matus UHLAR - fantomas <uh...@fantomas.sk> wrote: >> On 31 Jul 2016, at 22:12, Benny Pedersen <m...@junc.eu> wrote: >>> i bet greylist is cough invalid mailservers at the doorstep, it could be >>> that postscreen is bad aswell ? > > On 01.08.16 07:46, @lbutlr wrote: >> Sure, if by “invalid” you mean Amazon, most banks, several airlines, large >> mail services, and many many others. >> >> Nearly any company with multiple mail servers will send mail from any of >> their servers, and may retry from a different server than the initial >> attempt, thus resetting the greylist. > > while we're at it, I really don't understand why they do it like this. > what's the point behind changing IP address after each delivery attempt?
It’s not necessarily intentional. I have 100 mail servers. I send a mail to someone. It goes to one of the 100 mail servers to get sent out. It has a temp fail. I queue the mail up send again in 15 minutes. It goes to one of the 100 mail server to get sent out. Lather, rinse, repeat.
