I read the requirements at CFR 233.3, and the requirements are laughably slim. All you need is to (1) be a cop and (2) give a plausible reason. The USPS is not required to validate your reason, or do anything other that verify that the regulatory requirements have been met.
And there are no regulatory restrictions on what they can share, except one. They cannot include anything posted from any person to their known attorney.
So you can actually have all the cookies, except the white chocolate and macadamia nut cookies, for up to 30 days at a time.
And there's the problem. Why the hell doesn't that require a warrant?
Other than that, I really don't expect the Post Office to ever do anything but comply with lawful requests. What's the alternative? Do you want the Post Office conducting internal investigations of postal customers?
Oh, they do that, too. The other half of the mail cover regulation specifies the requirement for when the postal inspectors want one for their own use.
And there are no regulatory restrictions on what they can share, except one. They cannot include anything posted from any person to their known attorney.
So you can actually have all the cookies, except the white chocolate and macadamia nut cookies, for up to 30 days at a time.