[Inkscape-user] about spam?

Hi Friends, I was just looking at a message that looks like it was sent to 3 Inkscape mailing lists. But it looks quite spammish. I'm just curious how spam in the list is handled. It *could* be spam only for me, that was made to look like it's from the Inkscape lists, to fool me. I don't know much about mail headers and such, but it does look like it was sent to the lists, to me. I won't say exactly which message, in case it's not spam. But how is spam kept out of a mailing list?

Thanks, brynn