On September 2, 1817. Ds, dealers in wool, offered certain quantity of wool to Ps at a certain price, requesting an answer 'in due course of post'
*Note* Offeror can dictate terms of acceptance -> Call me to accept the offer then and email is invalid and contract has not been made.
By mistake, Ds misdirected the mail. It was not received by Ps until September 9th.
Ds had sent mail accepting the offer December 5th.
Ds received Ps acceptance Sept 9 (would have received it sept 7 if misdirection had not occurred)
Before Ds received Ps acceptance, they had sold the wool to a third party.
Was there a contract between the parties?
Postal Rule: Contract is made when mail is sent, not received.
The defendants argued that there could not be a binding contract until the answer was actually received, and until then they were free to sell the wool to another buyer
Sept 5 is the date the contract was made by the mail due to 'Postal Rule'