Yes. When considering timeliness of a payment, banks are not obligated to honor postmarked dates. In determining lateness, the bank goes by when the payment is received, not when it was mailed.
Generally, the bank must credit a periodic payment (covering principal, interest, and escrow amounts) to the consumer's loan account as of the date of receipt, except when a delay in crediting does not result in any charge to the consumer or in the reporting of negative information to a consumer reporting agency.