what is spoofing?

Spoofing is the masking of information to appear legitimate. Spoofing is rather complex to do so we don't see it too often but it's also highly successful. This is why I have programmed the email server to add [External] to your email addresses.

Example

One time, the staff received an email from Sam claiming that he needed them to respond quickly to him via email. This was definitely Sam Spam but what made this so tricky is that the email address shown was sferguson@tfcanglican.org. But was it really from Sam? 

No.

Why? Because in the subject line was [External]. This is placed by our email server on the subject line of any email that come from outside our network. When I look at the headers, I can see the actual email address - abx9ac@gmail.com. If it had been legitimately from Sam, [External] would NOT be in the subject line.