So, you're basically proposing that people voluntarily opt-in to a world-wide database of email address/topic-of-interest pairs? No way. Absolutely, no f-ing w

So, you're basically proposing that people voluntarily opt-in to a world-wide database of email address/topic-of-interest pairs? No way. Absolutely, no f-ing way would I ever let my address get in there, and I would strongly advise against any of the users I support ever volunteering such information either. If you're truly seeking interested parties to email about a topic, a few minutes spent on Google should let you find folks who blog, post to public mailing lists, or otherwise mark themselves online as interetsed in that area. The only value to a fully machine-readable database of the sort you describe would be for lazy cold-calling salespeople and spammers/phishers...though the separation is really only one of degrees.