Does DMCA apply for postal companies from delivering copyright infringed material?
If yes there seems to be no form to file one in case I get information of someone doing so.
No. the DMCA is the implementation of an international treaty, and has the following chapters (emphasis mine):
The DMCA amends Chapter 5 of title 17 in the shape of 17 USC 512. It only cares for digital media on the internet. It doesn't care for tangible items, and the postal service only delivers tangible items.
Even if the DMCA could in any way be applied to postal service (It can't), there is a much larger problem: An internet provider can potentially check all the sites on his servers and remove access to them, because sites are public. However, the postal service knows only 4 things about the packages and letters they carry:
Only for international deliveries, a list of contents is added, and that is not for the postal service but the customs office. Postal service doesn't know what is in the box, and technically isn't even allowed to know, unless it is clear from the packaging. That is called the Secrecy of Correspondence, protected since Ex parte Jackson 96 U.S. 727 (1877)!
As a result, the Postal service is not allowed to open sealed deliveries unless there is a very specific reason from a list. USPS has postal inspectors. The list when they may open deliveries contains only 3 big items: