There's a new spam going round that we started seeing last Friday. The subject line consists of a (seemingly) random string of characters composed of uppercase letters and numbers, and the body text contains two words: Hillo<number> followed by a string of numbers and lowercase letters (letters optional in the limited examples I've seen).
From: eldonxv4 [firstname.lastname@example.org]
To: A name that's not mine
Looks a little random but my bet is that it is either broken spamware or address harvesting. I think we can expect to see another spam run within the next couple of days. That's typically the way it worked in the past.