Yahoo's feature (I think it requires Yahoo Mail Plus) is perhaps a better approach: If your Yahoo email address is "[email protected]", you create a base name that has nothing to do with your email address, like "FTguy". You then create disposable email addresses by appending any additional keywords to the base name, like "[email protected]". This way the disposable address can't be mangled back to your real address. Yahoo requires that the base name be different from your email address.