Postal Service Emergency Assistance Act This bill provides emergency funding for the U.S. Postal Service (USPS). Specifically, it establishes and makes appropriations to a Postal Service COVID-19 Emergency Fund from which the Department of the Treasury shall transfer up to $25 billion certified by the USPS as necessary to cover lost revenue or operational expenses resulting from the COVID-19 (i.e., coronavirus disease 2019) pandemic. Treasury shall lend the USPS, under the Coronavirus Aid, Relief, and Economic Security (CARES) Act, up to $10 billion at the request of the USPS subject to the terms and conditions of the note purchase agreement between the USPS and the Federal Financing Bank in effect on September 29, 2018. The USPS shall, in coordination with its Board of Governors, develop a plan to ensure the long-term solvency of the USPS.