9.3 is nothing to get excited about:
1.
[+] Apache port change - you can change Apache web server port to use a lightweight high-performance web server, such as nginx, as a front-end web server, and move Apache web server to back-end.
2.
[-] Certificates from repository of domain set on exclusive IP address are reset when domain backup is restored bug is fixed.
3.
[-] The "Applications" link appearing in the left frame for domain administrator's main menu when applications management is not supported by license bug is fixed.
4.
[-] Enabled mail greylisting loads server's CPU/memory hardly bug is fixed.
5.
[-] A pattern not listed in greylisting configuration was automatically applied bug is fixed.
6.
[-] Timeout in postfix-queue prohibiting to send messages with big attachments from Parallels Plesk Panel server bug is fixed.
7.
[-] Syntax error in the backup-unpack utility bug is fixed.
8.
[-] If a message cannot be sent, sender receives a message with invalid field from=#@[] bug is fixed.