I made the installation now more then 15times (I The Perfect Server - Ubuntu 20.04 with Apache, PHP, MariaDB, PureFTPD, BIND, Postfix, Dovecot and ISPConfig 3.2 (Beta)) and ISPConfig works fine, but I can not send emails out and can not send emails to the email address are all returned with 550 5.1.1 Recipient address rejected: User unknown in local recipient table. The Firewall on the server was disabled and on Alibaba Cloud I open all ports, which has to be open. The DNS for the mailserver is set with mail.wanliju.asia. The mail.domain. is also set to the Internet IP 18.104.22.168. I run the MX lookup on MXtoolbox.com for wanliju.asia and DMARC Record Published, DMARC Policy Not Enabled and DNS Record Published shows up ok. Also the Test Email Server shows OK. I have no idea anymore where to look. May be some can tell me, what I have to look for, if I do the installiation in a cloud (Alibaba Cloud). Thank you!