It certainly is a service offered by the big 5 canadian banks... as far as i know with an interac email money transfer nobody can take money from your account, they can only send it to you...
generally speaking the process is as follows:
1.sender tells receiver the answer to a challenge question
2. receiver answers question
3. receiver can then deposit the transfer into their account at their FI.
im not sure if US banks support this or not however. and like anything banking related, if you suspect its a scam you should report it to your FI and provide as much detail as possible, and it goes without saying, you shouldn't give up any personal or banking data!!!
--Dave