Stupid spammers. Three days ago I planted spam trap addresses in HTML comments on my pages here at muensterland.org. Very obvious spam trap address and in an HTML comment. These addresses are only on the web, nowhere else. Never used and nothing that could be connected through combination with other address parts. And what happens today? The first spammers are spamming the addresses. Ugh.
So if you really want to know why you're getting spam on your addresses: check out which websites your email address appears on. The chances that that's the reason are quite high. Even if it only shows up as author information in an HTML comment...
Well, websites on muensterland.org are spam-safe, another argument for a site here :-)