Spam without purpose

From korrekt.org

15 Dec 2008. A spam mail I just received asks me to buy an oil tanker (7,000dwt). Apparently, I am not the first to get such offers. The obvious question is: why? (I note that there is no attachement, no suspicious or different HTML component, not even links to browse to). So here are some hypotheses.

1. The mail really tries to sell oil tankers. The company (or whatever it is) exists and tries to get rid of those beasts. Among millions of recipients, the spam actually finds someone who really wants to buy a ship.
2. The mail is intended to verify/capture email addresses by provoking responses to the unusual offer.
3. The mail is a form of Nigeria scam that unfolds only later, e.g. when someone replies with a bogus offer to buy the ship.
4. The spam is a demonstration or assessment of global reach, conducted by a novel spam marketing provider who wants a way to measure how many clients actually read such spam. The unique subject of the mail might be useful for distinguishing it from other spam.
5. Spam providers discover that machine-learning-based spam filtering algorithms are less effective or reliable if some spam (marked by users who received it) does not fit the established schemes at all.
6. It is a joke by someone who has the means to do this kind of attacks.

I am not really convinced by any of those. I would not invest a large sum of money based on an anonymous email, ruling out (1). Item (2) would be much easier by other means, e.g. when including an external image in the HTML-part of the mail. The Nigeria scam theory is possible, but the mail does not really fit the scheme of other mails of this kind. Regarding (4), it does not seem to be a very reliable instrument, and, while it is unusual, it is not crafted in a way that would provoke maximal visibility. Item (5) is similarly unlikely: the mail should contain more text, and many more emails of similar kind should reach us. In any case, regular spam mails already feature bogus text to confuse spam filters – there is no reason for sending a dedicated mailing just for this. Finally, considering (6), the mail is really not funny enough, is it?

So, what remains is the depressing suspicion that the only intention of this mail was to make me waste my working time. It was a success then.

Edit: Some comments found on the web suggest that (1) or (3) are most likely. At least some people claim to have received a response when contacting the person given in the email.