Was just thinking about a comment in Satoshi's paper and thought of a slight twist and curious if this might be the way to avoid us getting spam forever...
If when sending an email we include an extra header of 'my private email key' which is just a bitcoin private key.
If that address has more than X bitcoins in it the email will appear in your 'trusted email folder'. If it's not spam, everything is good and life continues. If however it's an unwanted email you simply collect their bitcoin (and send it to a charity) and this therefore cost the sender real money and will stop the email from appearing in other people's 'trusted email folder' as that address now has a 0 balance.
The value 'X' can be user specified so perhaps myself I'd only set it at 0.001 where as Microsoft directors would require 1BTC in the account to receive a trusted email as they probably get more spam?
It does mean that who ever you email you must trust them to not steal your money but that sounds quite a sensible if you're really keen on making sure you get someone's direct attention.
This opens the door for other possibilities such as making your email public!! Yikes!!
Secondly this could be applied to your telephone too, imagine that... no more PPI calls as it would be costing people a fortune to run these annoying marketing campaigns if you could just press a button after the call to take their staked funds.
If it sounds sensible it seems all we need to trial it is an outlook plugin that can test a private key (perhaps via blockchain.info to begin with) and a button to 'donate' the received money to a charity.
Perhaps setting up a pending escrow transaction from the sender to the charity whereby the receiving client can decide to allow the transfer to happen to avoid malware theft?
I'm sure there must be flaws in this as it seems a potentially easy solution to eradicate spam so curious what I've overlooked?
If it sounds sane, anyone interested in helping code up an outlook plugin?