Ok let me clarify a little better on what I am trying to achieve.
I would like to build a linux box (Ubuntu preferably) - this linux box is going to host an email spam filtering service that I can connect domains too so that any email sent to these domains is checked for virus and spam etc. then delivered to the intended recipient's mailbox (similar to Ironport, SMX etc.). My question is, does anyone know of an open source piece of software that will allow me to achieve my intended need (I have seen Xeam, DSPAM but havent used them).
Secondly, I would like to archive any email - so that if the mailservers at the recipients domain is down (for whatever reason) they can be retrieved from the Archive.
If anyone out there has used Mail Marshall, Ironport, DSPAM, SpamSoap, SMX Mail Security etc... - I would like to build a test box similar to this.
If I need to clarify my question a lot more - please do let me know - I am more than happy to explain my question in many different ways or languages :)