First Class Mail
Estimated delivery time is two to three days.
Typically two to three days to most locations in the US (specific delivery standards may be available with postage is calculated). This is not a guaranteed service.
Express Mail Service
Items are delivered to the addressee (recipient) by noon or 3:00pm the next day, or noon or 3:00pm the second day.
(PO to PO) Items are available for collection by the recipient by 10:00am the next day or second day (or next day or second day that the destination Post Office is open for retail business).
Typically two to nine days in the 48 contiguous states for most origins and destinations. Specific time standards may be available when postage is calculated.