It is a spam email. That's a for sure. It is most likely one of those emails that has words (random ones) in it. Do you have your email program to accept only plain text email? That all said, I have a theory that this is just to check that your email is running and what words seem to work through spam filters. This link also suggests that it might be a high noise idea (that is, send so much traffic that it confuses the program).

The only way we'd know why these and blank emails are sent is to ask a company that sends out spam.