Have you ever felt the need of a fake email to win an argument, prove someone wrong, or just to prank a friend?
If yes, then you will be pleased to know there are tons of great online services available for this job. Take EMKEI.CZ for example. This website offers the feature to send emails to any email ID, on behalf of any one (that is, from any email ID)
This is a prime example of email spoofing, taking benefit of the fact that the SMTP servers aren't providing any mechanism for the authentication of the senders' email. But you don't need to know all these jargons, just fill the required details, and you're ready to go.
The interesting part of this whole trick is, when the receiver gets the email, and replies to it, then that reply goes to the real owner of that email ID. The email passes any filter and doesn't land in the SPAM folder.
To know that if you stand on the other side of the prank, all you gotta do is, view the source of the email, and look for the IP address of the sender, you can then visit sites like IP2LOCATION which can help you trace the location of the sender, the ISP, domain and other useful information, this can be enough to figure out if the email is genuine or fake.