just save the attachment if you have it as a txt file and open in notepad, if you know any programing lingo it should be pretty "basic"

Or better yet read the mails thru a telnet session if u still have it.
Basically most spam filters, will check for trigger words that classify it as a spam, there are VBS scripts that will now do a simple translation even something along the lines of a bunch of text say like
"
Rnea lbhefrys zvyyvbaf
"
and then a "decryption sequence that rearranges" text back to what it was .. say in this case a 13 character shift [which is common esp in usenet messages].