BOAC,
What I was not sure about is that once an email is in the email database of outlook will a virus checker pick up its signature or will the signature change with the compression into the database.
My thought was a databse of compressed virus attachments would look different to a virus scanner than a series of files, a be it a single incomming email, or a single file on a hard drive.
Thats why I was looking to see how old messages could be checked.