I don't think you become a criminal when you are tricked into depositing a stolen check in your account, but since you entered the chain of payment, you will certainly have to demonstrate the nature of your involvement, which could be a difficult task if you are not properly documented. Can you prove you are inocent showing only emails? (not likely)

Banks are part of the chain of payment and also need to prove that stolen checks were deposited by a customer, etc. The key safety rule here is: "know your counterpart". This means you have to identify him positively and document the transaction. This is advisable for all transactions.

Take care,
Luiz