John and David are young entrepreneurs that would like to enter into a partnership agreement. John lives in Cape Town and David in Limpopo. John draws up the agreement and forwards the agreement via email to David who promptly signs and returns to sender. A week later John has second thoughts, as he has found a new investor and would like to withdraw the contract and claims that the contract was not concluded and is therefore invalid. David claims that the contract was concluded. How would you advise parties in this instance. Rely on case law to support your