Can Homeland Security open private domestic US mail without a search warrant?

[astro]

I saw this story (link below) and just wondered what the limitations were on private domestic mail within the United States?

Homeland Security opening private mail
Retired professor confused, angered when letter from abroad is opened

[SmackFu]

So you aren’t asking about the cited case, right?

Because the case in the article seems like a fairly standard Customs Service (now under DHS) opening international mail to inspect it. Probably for child porn, if it was from the Phillipines.

[Duckster]

DMM 333 - 3.2.1 Inspection of Contents

[6-1-05] First-Class Mail is closed against postal inspection. Federal law and USPS regulations restrict both opening and reviewing the contents of First-Class Mail by anyone other than the addressee.

Source: USPS Domestic Mail Manual

However, sending mail via other classes does not guarantee privacy. For example, there is no right to privacy if you send something via Media Mail. So if you send the CD or DVD to your friends via Media Mail, the post office can open the package and inspect its contents without a warrent.

[CynicalGabe]

@Duckster

So if you send the CD or DVD to your friends via Media Mail, the post office can open the package and inspect its contents without a warrent.

I echo that - there are signs saying so prominently in every post office.