Email spoofing is the creation of email messages with a forged sender address. Because the core email protocols do not have any mechanism for authentication, it is common for spam and phishing emails to use such spoofing to mislead or even prank the recipient about the origin of the message. Technical detail When an SMTP email is sent, the initial connection provides two pieces of address information: MAIL FROM: - generally presented to the recipient as the Return-path: header but not normally visible to the end user, and by default no checks are done that the sending system is authorized to send on behalf of that address. RCPT TO: - specifies which email address the email is delivered to, is not normally visible to the end user but may be present in the headers as part of the "Received:" header.Together these are sometimes referred to as the "envelope" addressing, by analogy with a traditional paper envelope, and unless the receiving mail server signals that it has problems with either of these items, the sending system sends the "DATA" command...