I get how the client can send messages to a contract. How would I implement the opposite, ie. a contract sending a message to a "client" (albeit running as a server)? By way of a simple use case, let's say I have a MyCoin contract and I want the contract to email the account holder whenever he receives MyCoins.
I'm new to Ethereum, so if the answer is rtfm, please link me up.
Related. Can anybody recommend a good tutorial/video that approaches Ethereum from the top-down, rather than bottom up. I have consumed several resources that start of discussing Bitcoin and block chains, and then have a brief mention of app development. I'm looking at something which starts at, and focusses on app development.