Hi,
Tracing the origins of email is a fairly arcane art but can be done, but is resource hungry.
There are programmes that can be downloaded from the Internet to assist you in this but before you start on this it is important to have an outline knowledge of how email gets from sender to recipient. Its also important to remember that some email clients are set up to automatically block an attachment that is executable.
For example a file ending in .exe is an executable and is often automatically blocked either by the email client or by the ISP (Internet Service Provider) The reason for this is that an .exe file can be malicious and severely harm your system when it runs. On the other hand the .exe file may be perfectly legitimate, and be very useful and provide useful and important services and benefits.
It is necessary therefore to establish the safety of a particular file (running appropriate anti-virus/antispyware scans) and thoroughly researching the file before even considering overriding the security settings that you have in place. If in any doubt the best advice is to keep well clear of it.
For extra information on starting to trace the origins of the email the following site offers a basic overview that might help you get started.
http://www.usus.org/...nts/tracing.htm
The bad guys are unfortunately very adept at both covering their tracks and masquerading under false colours, so you will need to be alert, diligent, and tenacious in your quest to avoid being defeated by the deliberate obfuscations that they employ.
Best of luck
Regards
paws