a client pinged… he has lost his database for a site which he had spent close to 6 months on… he interpreted a mail from a script provider differently and ended up deleting the db…. the backup is from when he had first set it all up. I had setup his server and used to [...]

Opcode caching helps!
From the eaccelerator home
eAccelerator is a free open-source PHP accelerator, optimizer, and dynamic content cache. It increases the performance of PHP scripts by caching them in their compiled state, so that the overhead of compiling is almost completely eliminated. It also optimizes scripts to speed up their execution. eAccelerator typically reduces server load [...]

Well how about a challenge-response mechanism. How about asking the sender to ensure that they sent you the message before letting the message reach your mailbox.

Ever wanted to extract the audio stream from a music video to make it easier to carry on your mp3 player? Well we have developed an application that allows you to do just that!
Not only can you extract the audio from the video you can also extract the optimized flv from the video and download [...]

This writeup illustrates how you can enable secure roaming access to an smtp server while simultaneously adding a further layer of security to your postfix mail server. Not 100% guaranteed to keep thieves at bay but very effective.
It works on the principle that if you have an account on the server you are authorized to [...]