The new deliveries will begin right away and only happen during the holiday rush.
For now the deal is only with Amazon but the USPS confirms they will soon branch out to accommodate other retailers.
The service will be a money maker for a service that has been traditionally in the red and helps the postal service get an edge on competitors.
Other delivery companies like Fed-Ex and UPS do not deliver on Sunday’s.
Postal Service worker Sue Brennan told the Los Angeles Times the number of letters being mailed has gone down "extremely."
However at the same time, the number of packages being shipped "increasing in double-digit percentages."
The Sunday service will begin in New York, Los Angeles, and some of their surrounding communities but is expected to expand to cities like Houston, Dallas, Phoenix, and New Orleans
The best news for shoppers is, there won’t be an upcharge for the 7th day deliveries
This won’t interfere with the plan from Congress to stop Saturday mail delivery.