I'm moderator in a very small forum. It has areas for many different IT-related topics (in German), and several sub-forums (in English) that serve as support areas for various open source libraries. Therefore, the forum is open for everyone, without registration: Completely anonymous posts are allowed, so that people don't have to register only to ask something about one of the libraries.
Of course, the usual cat-and-mouse game between spammers and good guys is played. I am not an administrator, and not familiar with the technical infrastructure behind this. But there are some CAPTCHA-like hurdles for posting, some blacklists, and "suspicious" posts may have to undergo a moderator review before being published.
It's working quite well. The classical advertising spam is usually caught, and only occasionally one of them appears as "moderated" and is then deleted by a moderator.
But recently, there have been ... "non-classical" spam posts: Anonymous posters have posted greetings. These, of course, went through all security nets, because they are basically perfectly legitimate posts - one recent example:
I'm Will from Bosnia :-) I'm pretty sure we can enjoy a lot of great moments with each other :-)
See you on the other topics!
In fact, I once did keep (and not delete) some of them, because I thought that they might really be legitimate. But there are reasons to assume that these are "spam" posts: They are posted in arbitrary sub-forums, sometimes even as answers to other posts. The posters seem to be never seen again afterwards. There is a very small communtiy of registered/regular users, but this group is posting only in German, so it's nearly impossible that someone just wants to join us by posting anonymously and in English. These posts seem to be created from various IP addresses, and - apologies for the possible cliché - not
I thought that these posts might be sorts of "tracing bullets": A spam bot does the post, and if it's still there after a while, it assumes that the forum is unmoderated and it starts to flood it with "real" spam. But this seems unlikely.
Can anybody imagine what could be the purpose of these posts?
EDIT: Another moderator indirectly pointed out the result of googling for "I'm Will from Bosnia", which strikingly confirms that these are spam posts. The purpose is still not clear, but the answers already list some options.