Whether emails can be considered as legl document largely depends on court and judges, so it has to be case by case.
The chain of emails have to clearly demonstrate that one party intends to enter an agreement with all meterial terms and the other party explicitly accepts the terms, then it can be considered that a contract/agreement has been formed. In this case, there is a good chance the emails can indded be adimmited as legal document.
But again this is determined by court and presiding judges.