Interesting article. I think the reasoning about multiple identities and adresses is spot on, as is the use of signature and stamps to limit spam. I do think,

Interesting article. I think the reasoning about multiple identities and adresses is spot on, as is the use of signature and stamps to limit spam. I do think, however, that use case of receiving mail from strangers is a much bigger case and can't be handwaved away. I was thinking of something similar lately, coming at it from the social networks angle. I was thinking about personas in social network setting (what google+ attempted with circles), ownership of your data and social links, and the thought process led me to something very similar to what OP is describing.