create a validation rule create a validation rule that displays an error message and prevents a user from creating or updating a contact if two conditions are both true. create a validation rule: rule name: contact must be in account zip code operator: and (return true if both conditions are true) define two error conditions: the contact is associated with an account id hint: use the isblank and not functions. the contact mailing zip code is different than the account shipping zip code hint: use the api names (mailingpostalcode and shippingpostalcode) and the <> (not equal) operator. enter an error message for the validation rule