E-mail spoofing is a term used to describe (usually fraudulent) e-mail activity in which the sender address and other parts of the e-mail header are altered to appear as though the e-mail originated from a different source. E-mail spoofing is a technique commonly used for spam e-mail and phishing to hide the origin of an e-mail message. By changing certain properties of the e-mail, such as the From, Return-Path and Reply-To fields (which can be found in the message header), ill-intentioned users can make the e-mail appear to be from someone other than the actual sender. The result is that, although the e-mail appears to come from the address indicated in the From field (found in the e-mail headers) it actually comes from another source.

Occasionally (especially if the spam requires a reply from the recipient, such as the '419' scams), the source of the spam e-mail is indicated in the Reply-To field (or at least a way of identifying the spammer); if this is the case and the initial e-mail is replied to, the delivery will be sent to the address specified in the Reply-To field, which could be the spammer's address. However, most spam emails (especially malicious ones with a trojan/virus payload, or those advertising a web site) forge this address too, and replying to it will annoy an innocent third party.

Prior to the advent of unsolicited commercial email as a viable business model, "legitimately spoofed" email was common. For example, a visiting user might use the local organization's smtp server to send email from the user's foreign address. Since most servers were configured as open relays, this was a common practice. As spam email became an annoying problem, most of these "legitimate" uses fell victim to antispam techniques.

This Service Works Perfectly And is Free Of Charge