Protect Our Letter Carriers Act of 2024 This bill requires or authorizes certain actions related to the U.S. Postal Service (USPS). The bill requires the Department of Justice to appoint an assistant U.S. attorney in each judicial district to coordinate and supervise the investigation and prosecution of various crimes related to postal services (for example, assault on a postal service employee, breaking into a post office, or obstruction of mails). The bill also requires the U.S. Sentencing Commission to amend sentencing guidelines to provide that the assault or robbery of a postal employee shall be treated the same as the assault of a law enforcement officer. Additionally, the bill authorizes appropriations for the USPS to install high security collection boxes and replace older versions of the universal mailbox key with electronic versions.