i solved the problem in /etc/postfix/main.cf on line inet_interfaces = loopback-only change to localhost and now is working. Thanks for your help.
Bingo, that solved my issue with notification emails not working after the upgrade to Arrakis. Logs pointed to a DNS issue, so I troubleshooted by verifying /etc/resolv.conf and /var/spool/postfix/etc/resolv.conf were populated correctly, and also tried alternate DNS servers.
I had also edited /etc/postfix/main.cf and changed line inet_interfaces = loopback-only to inet_interfaces = all, yet this did not work! All hail localhost.