Is it possible somehow with ethereum smart contract implement proof of identity and email check?
Is there a need to do external call or everything can be implemented in blockchain. How to add then new identity to blockchain to check it later?
I am searching this topic for a while without any success.
Unfortunately not, contract on Ethereum EVM cannot call others external process, only call another contract by the address of the given contract. Although is possible to create external agents known as Oracles which has the ability to call external process like API calls, send emails and receive some sort of interaction and applying those changes to a contract on the Ethereum network, sort of proxy through the between two worlds. To achieve that can you should use the JSON-RPC connection which can be enabled in any Ethereum node that you control, of course, to interact with you contract directly after receiving the external call.
