Hi, I state that I do not understand anything about linux, I improvised to install ispconfig following a tutorial, I must say that everything went well except the e-mail part, however I try to expose my problem translated with the translator hopefully well. I installed ISPConfig Version: 3.1.15p3 on debian I set up an email account with rondocube I can send mail regularly but I cannot receive. When I send a message to the mailbox I have configured, it returns the following message: "Reason: This is the mail system at host smtp-36.iol.local.I am sorry to have to inform you that your message could not be delivered to [email protected]. The message is attached below. The remote mail system said: 554 5.7.1 <[email protected]>: Relay access denied " I entered my provider's panel and configured the record and configured an MX record that points to my FQDN (xxx.xxx.it). My provider's assistance confirms that the configuration is ok. I went around a lot on the forums I saw that there are many open discussions about my problem, but I could not solve it anyway, if something can help I tried to run some commands: Code: Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent permitted by applicable law. Last login: Fri Oct 16 11:48:31 2020 [email protected]:~# less /var/log/mail.log Oct 13 15:06:15 network1 postfix/postfix-script: starting the Postfix mail system Oct 13 15:06:15 network1 postfix/master: daemon started -- version 3.4.14, configuration /etc/postfix Oct 13 15:06:20 webitalia postfix/postfix-script: stopping the Postfix mail system Oct 13 15:06:20 webitalia postfix/master: terminating on signal 15 Oct 13 15:06:21 webitalia postfix/postfix-script: warning: symlink leaves directory: /etc/postfix/./makedefs.out Oct 13 15:06:21 webitalia postfix/postfix-script: starting the Postfix mail system Oct 13 15:06:21 webitalia postfix/master: daemon started -- version 3.4.14, configuration /etc/postfix Oct 13 15:06:36 webitalia dovecot: master: Dovecot v220.127.116.11 (f79e8e7e4) starting up without any protocols (core dumps disabled) Oct 13 15:06:41 webitalia dovecot: master: Warning: Killed with signal 15 (by pid=9955 uid=0 code=kill) Oct 13 15:06:42 webitalia dovecot: master: Dovecot v18.104.22.168 (f79e8e7e4) starting up for imap, lmtp, pop3 (core dumps disabled) Oct 13 15:07:04 webitalia postgrey: Process Backgrounded Oct 13 15:07:04 webitalia postgrey: 2020/10/13-15:07:04 postgrey (type Net::Server::Multiplex) starting! pid(11671) Oct 13 15:07:04 webitalia postgrey: Resolved [localhost]:10023 to [127.0./var/log/mail.log Code: [email protected]:~# less /etc/postfix/master.cf # # Postfix master process configuration file. For details on the format # of the file, see the master(5) manual page (command: "man 5 master" or # on-line: http://www.postfix.org/master.5.html). # # Do not forget to execute "postfix reload" after editing this file. # # ========================================================================== # service type private unpriv chroot wakeup maxproc command + args # (yes) (yes) (no) (never) (100) # ========================================================================== smtp inet n - y - - smtpd #smtp inet n - y - 1 postscreen #smtpd pass - - y - - smtpd #dnsblog unix - - y - 0 dnsblog tlsproxy unix - - y - 0 tlsproxy submission inet n - - - - smtpd -o syslog_name=postfix/submission -o smtpd_tls_security_level=encrypt -o smtpd_sasl_auth_enable=yes ^M -o smtpd_client_restrictions=permit_sasl_authenticated,reject # -o smtpd_tls_auth_only=yes # -o smtpd_reject_unlisted_recipient=no /etc/postfix/master.cf I thank you in advance for your availability ..