From the release notes:
Parallels Plesk Panel 9.0.0 update-2
1.
[-] Wrong detection and display of mail queue capabilities of Postfix mail server in Parallels Plesk Panel GUI bug is fixed.
2.
[-] Inability to send mail when SELinux is enabled and KAV is used as an anti-virus bug is fixed.
3.
[-] Inability to send mail due to self-signed SSL certificate used by Postfix mail server bug is fixed.
4.
[-] Mail message headers being corrupted after switching to Postfix with enabled SPF protection bug is fixed.
5.
[-] Corrupted e-mail messages delivered after switching from Qmail to Postfix bug is fixed.
6.
[-] SpamAssassin not processing messages sent to mail aliases after the upgrade bug is fixed.
7.
[-] Spam messages are marked as a spam but are delivered to mailboxes anyway even when spam protection policy is set to reject spam bug is fixed.
8.
[-] Short mail account names authorization not working after the upgrade from Plesk 8.x bug is fixed.
9.
[-] Inability to connect to local SMTP mail service when Qmail mail server is used bug is fixed.
10.
[-] Apache web server failing to start after Atmail is removed from the system bug is fixed.
11.
[-] Incorrect processing of web applications installed on virtual host when corresponding application distribution is absent in the Application Vault bug is fixed.
12.
[-] Stoppage of xinetd service after the installation of Parallels Plesk 9.0.0 on Fedora 8 based server bug is fixed.
13.
[-] Inability to unable to upgrade Plesk 8.6 with latest update to Parallels Plesk Panel 9.0.0 through Parallels Products Installer on servers using openSUSE, SUSE Linux Enterprise Server, Fedora Core 5 and Fedora Core 6 OSes bug is fixed.
14.
[-] Errors with SELinux during the upgrade to Parallels Plesk Panel 9.0.0 on servers using RedHat Enterprise Linux 4 and CentOS 4 bug is fixed.