I had problem with non working postfix server (after unsucessfuly completed ISPConfig installation) and I solved it with removing it (yum remove postfix) and installing it from source (postfix 2.9.4, built as root). I had to install 2.7 or newer because virtualmin forced me. After that, mail server started to send test email and could get it. But, after that, I noticed that I can receive outside emails but can not send mails to any other domain (only to other emails on my domain, nemogucamisija.com). Error code was: Then I noticed that postfix can not access certificate. Disabled TLS but now I can not set Transport Mapping, cause postfix can not access /etc/postfix/transport . Tried and I know building it as a root was not smartest idea, but tutorial required it. So, what I shoul do to fix this? Or, any other solution to enable sending emails to other domains than my own? Thanks in advance!