Hello, I am recently facing a small problem. I have sent some emails to different addresses and after a few days I receive a response from several addresses like: Where is the problem, it seems strange that different servers to respond with the same error at the same time. Is it from my server? I am using an older version of Fedora (Core 4) with postfix, spamassasin, dovecot.
Ok, I have contacted the parteners I am trying to send emails to and they have something like: in their logs. From what I understand is they have sender verify callout enabled on their server (exim). My server 25 port isnt blocked, but I am using spamassasin which may delay the responses to Exim's commands, still i have added their host in our whitelist with no success. Anyone knows a fix for my postfix server?
