What time does mail normally get delivered?

The US Postal Service does not guarantee a delivery time for standard mail delivery. Delivery times will vary based on your area, however, mail is almost always delivered no later than 5pm. If you are expecting a package or letter to arrive via Express Mail, it will be delivered no later than 3pm.

Wednesday, February 01 2012
Source: http://faq.usps.com/eCustomer/iq/usps