The likelihood of becoming infected with the virus that causes COVID-19 from mail, newspapers, or packages is quite low. Out of an abundance of caution during the pandemic, when handling or reading your mail, the newspaper, or packages, it would be best to avoid touching your face. Also, wash your hands with soap and water after handling, and keep mail, newspapers, and packages in one spot in your home.
A study did find that the COVID-19 virus can remain viable on cardboard for about 24 hours, and up to 3 days on plastic. However, this is under laboratory conditions using lots of virus, and unlikely to be representative of most real-world situations.
Updated 3 December 2020