As the latest version of MaigicSpam does not support Red Hat Enterprise Linux Server 5, we would recommend you to upgrade your Operating System to Red Hat Enterprise Linux version 6 or newer.
Alternatively , please email us at:
and we will provide you with the package of the previous version of MagicSpam that supports RHEL version 5.
Please note that if you install older version of MagicSpam in your system, you should turn the automatic updates for MagicSpam in your Plesk off, in order to prevent MagicSpam from updating to the latest version automatically.
We hope this information helps.