What Pecunia does is not very risky if you know what you are doing, I've done that myself a few times.
It is a virus.
Some of the virus are coded to claim they come from a specific compagny, to make them look more trustworthy they even use a mailaddress from that compagny, most common is Microsoft, IBM, Norton and McAfee, Winzip is new to me. A virus can also take a mailaddress in your adressbook and make it look like it is send from that address instead of from you.
If you know how to use Base64 you can do the same yourself. Base64 is a very old programming language made for sending mails without using the mailprograms we use today. Spammers very often use Base64 for making it harder to find them and spam their mailbox.
Pleasant words are a honeycomb, sweet to the soul and healing to the body. Pr. 16:24