USPS suspicion letter

If you decide to pick up the package make sure you have a good meal before you go. I hear jail food sucks.

USPS doesn't need a warrant to open packages most of the time.

If there is probable cause to believe the contents of a First-Class letter or parcel violate federal law, Postal Inspectors can obtain a search warrant to open the mailpiece. Other classes of mail do not contain private correspondence, and therefore may be opened without a warrant.
Frequently Asked Questions - United States Postal Inspection Service
https://postalinspectors.uspis.gov/contactUs/faq.aspx

Take the L and move on

If you're looking for a unwanted vacation, then go get it... If you want to travel freely, forget about it... And get rid of that letter!!! If you never saw it, you don't know what they are talking about... Stay away from the package...