The USPS is an independent federal agency not funded by tax dollars and its employees are not federal government employees. Since works produced by the USPS are not produced by federal government officers or employees they are copyrightable.
Well tbh who can blame them? the service stinks, the employees <at least at my local> are so rude as to border on the psychotic and they refused to allow us to put our mailbox at the end of our drive...we are the only house in our development where this is the case. they routinely refuse to deliver our mail and even when they do its ripped, dirty (at least i hope its dirt) or purposefully missing (yo anybody seen my socks i ordered over a month ago?) and its a never ending saga. she (the local pm) is awful to us all the time. whole checks have gone missing and needed to be reissued.
i had hopes of Thiel/OUTBOX but they went about the implementation a*backwards.
the machines the invented to scan the mail: check. the mail they wanted to scan: fail. instead of scanning the important mail (bank statements, insurance etc) they should have been scanning the junk and making the marketers pay for enhanced delivery to 1234MainStreet@ups.gov. customers could then just go through digital versions of offers etc and set it up to purge at various intervals. the pizza place, valpak now no longer need to print things thereby saving money and trees and we throw away less paper etc. they already have the EDD software and zip code db this was just one little step and it would have released the full value of the USPS. The royal post in the Uk and the Japanese post both posted record profits at at time when last mile logistics are a BIG deal...and we cant even deliver a postage stamp without problems.
Copyright law doesn't say anything about the federal employee standard though
> 17 U.S. Code § 105 - Subject matter of copyright: United States Government works
(a)In General.—
Copyright protection under this title is not available for any work of the United States Government, but the United States Government is not precluded from receiving and holding copyrights transferred to it by assignment, bequest, or otherwise.
If you look a few sections above in 17 U.S. Code § 101 which contains the definitions applicable to the copyright code "work of the United States Government" is defined.
> A “work of the United States Government” is a work prepared by an officer or employee of the United States Government as part of that person’s official duties.