Thomas:
I must reiterate that, given the relentless efficiency of spam-spiders, merely publishing a shadow email address on all web documents that your real email address reside on, and deleting all
email sent to both accounts is my current favorite anti-spam mechanism. Simple to DIY, and requires no centralization.
This approach assumes you are able to detect duplicates (which may be difficult to do if each spam sent out would be different, eg. using different sets of pseudowords - which is already being done in some cases, from the day antispam systems based on hashes of known spams were introduced), and depends on the duplicates actually reaching your both addresses within reasonable timeframe.
If one of the addresses was not ever used for legitimate purposes, then blocking all addresses that sent to this address should be an effective filter. Also, with the low cost of storage today, storing message hashes of known spam wouldn't take much space (not to say that this would be a good way of identifying spam). I was pondering recently the usage of a "web of trust"-type system whereby one could use communal whitelists with decreasing trust going outward as well as the opportunity to selected trusted sources - perhaps using authentication authorities for PK's as authoratitive whitelists, or not, as per ones choice. (Since PK's require identification for the issue of certs, it at least provides some chain of evidence. However, this negates the opportunity for anonymity). How feasible are implementations of such 'distributed' whitelists? (I'm assuming that entries from non-whitelist identified emails are permitted to send through on a challenge-response basis, and that once identified, users have the opportunity to add to such whitelist). And, is it possible to indentify a bit of information as coming from a trusted source, without identifying that trusted source and without resorting to the use of a TTP? -- Andrew G. Thomas Hobbs & Associates Chartered Accountants (SA) (o) +27-(0)21-683-0500 (f) +27-(0)21-683-0577 (m) +27-(0)83-318-4070