Note: Time Machine has default exclusion list that prevents it from backing up some important files in OSX Server. (Ref http://www.bill.eccles.net/bills_words/2008/08/designed-to-fail-apple-time-ma.html).
The file to edit to modify the exclusion list is as follows.
/System/Library/CoreServices/backupd.bundle/Contents/Resources/StdExclusions.plist
Update: Checked up on this in 10.6.3 and it seems that /var/spoool is now backed up.
I came across this when needed to update my wiki with Latex math symbols. The link is here. Very useful stuff. http://www.sitmo.com/latex/
Here are some links that provided me good resources to procmail configurations and allowed me to do what i wanted on my mail server.
The following document was found in the NSA site as an unclassified document. It serves as a good background to securing OSX an the various things to look out for.
Other interesting links includes
Interesting tools includes
The National Security Agency has good guidelines for Mac OSX. The security documents are available in PDF format on their OS Guides page for Mac OS X.