As simple as ABC

Was telling a friend how easy it is to spoof emails... but got a disbelieving expression back. Well here you go... its as easy as this. Test it but don't use it to spam others.
This service is even deadlier!!! It is meant to allow people to email attachments that are up to 100MB in size because most web-mail services (like Hotmail) enforce an attachment limit. But it can be used by those with malevolent intentions as well by inserting legitimate looking sender addresses and try to convince you to potentially open up a malicious file. So as best practice, always scan attachments that you download before opening them or don't bother downloading them in the first place if they are suspicious.
The Internet... it is both a boon and bane to society.