Monday is the first weekday of the government shutdown, and things are beginning to get real. But while the shutdown has affected government agencies and services in different ways, some are carrying on — including the US Postal Service.

That means post offices are open and mail delivery will continue despite the shutdown.

Although the post office is a federal entity, its operating budget is not funded by federal tax dollars. Instead, the Postal Service earns the money it needs to function every time you mail a care package to a relative or put a stamp on the upper right-hand corner of an envelope.

“The Postal Service receives NO tax dollars for operating expenses and relies on the sale of postage, products and services to fund its operations,” the USPS website reads.

USPS operations will not be interrupted due to the Gov’t shutdown, & all Post Offices will remain open for business as usual. Because we are an independent entity that is funded through the sale of our products & services, & not by tax dollars, USPS will not be impacted. pic.twitter.com/FS7kyvlONV — U.S. Postal Service (@USPS) January 20, 2018

While this method of funding might serve the Postal Service well during a shutdown, it’s worth noting that its financial situation is otherwise looking pretty grim. The USPS reported a $2.7 billion loss in 2017 and a $5.6 billion loss in 2016.

Last year, the House introduced a bill to restructure a 2006 law that requires the USPS to pay $5.4 billion to $5.8 billion to fund pension and health benefits for postal retirees. Although a House panel approved the bill, it has not been passed or voted on, leaving the Postal Service with a $6.9 billion debt to the government as of the last fiscal year.

But if you’re waiting for a letter or a package today, you can rest easy knowing it should arrive on time.