What is 'an internal user' ?

[powyco]

Until last week I've had few problems with spam, in spite of fairly heavy use of the Internet. The program I Hate Spam has dealt with the rubbish very well. However, I'm now getting innocent-looking emails with ordinary senders' names and subject matter, which I do not open. The most recent example is from Karen Smith, cocoa. When I try to report them to I Hate Spam I get the message 'this email cannot be reported as it comes from an internal user'. What does that mean ? No-one shares my pc, and it's free of all virus, trojan and spyware. Any advice or clarification very welcome.