<A target="_blank" href="http://blog.nashcom.de/nashcomblog.nsf/dx/issue-with-smtp-extension-managers-in-8.5.x.htm">Daniel Nashed ran into a memory overwrite problem with Domino 8.5.1 FP3 Server</A> on Linux when using SpamGeek that caused his server to crash. He's posted information to help you out.