IMHO: as an a holder of a anti-spam patent pending, I think its best to
let IPR holders approach us. Otherwise you put yourself in the
unenviable position of "authority" on patents. If you just say "these
are the IPR claims that have been submitted to us" that makes it clean
and simple, not to mention easy to maintain.
In some cases this would not be true. Take MailBlocks, for example - they
are claiming patents on all C/R systems. They have not approached, and
since their IP is of very general nature, thus we must approach them to
solicit a submission of IPR claims which is what I have done. Otherwise, we
might be working on a standard only to find out that it is patented. As for
the patents that are covering every nook and cranny of anti-spam, I am
agreeing with you. It would be an impossible task to catalog all patents in
the world.