Validates that the account Billing Zip/Postal Code is in the correct format if Billing Country is Canada.
AND(
OR(BillingCountry = "CAN", BillingCountry = "CA", BillingCountry = "Canada"),
NOT(REGEX(BillingPostalCode, "((?i)[ABCEGHJKLMNPRSTVXY]\\d[A-Z]?\\s?\\d[A-Z]\\d)?"))
)