Dear Paul,
there is a new message in the Magicspam extension that solves the problem - a download link.
This is the message:
Updated packages for MagicSpam for Plesk with Postfix!
By MagicSpam Support on Friday, January 17, 2014 | Type: security | Severity: high
This release addresses a milter vulnerability that was found that could potentially be used to access the underlying filesystem.
Release 1.0.5-4.1 is specific to packages for MagicSpam for Plesk (version 9.x and up) with Postfix. This release addresses a milter vulnerability that was found that could potentially be used to access the underlying filesystem.
Original risk was minimal as the MagicSpam service runs as a restricted system user but you are still encouraged to update to 1.0.5-4.1 if you are running MagicSpam for Plesk Postfix.
To upgrade, you can download our package at
http://download.magicspam.com. Simply remove the current module from your Plesk server via the Modules Management interface, then install the updated version in Modules Management.
best regards
Peter