Hi, I had installed my ubuntu server from scratch using this link. https://www.howtoforge.com/perfect-...sl-pureftpd-bind-postfix-doveot-and-ispconfig Now I am able to send mails to other domains but not able to receive mails. I got the below error Technical details of permanent failure: Google tried to deliver your message, but it was rejected by the server for the recipient domain hardcube.net by smtp.europe.secureserver.net. [18.104.22.168]. So please help me to solve this issue. Thanks in advance.