What is the legal test for establishing that a person who misused a government email address is responsible for the theft of government materials from a third party?

In establishing this type of theft, the prosecution is not required to introduce "direct proof of theft or taking from the mails .... [I]t is sufficient that the government show that the materials were mailed, that the addressees never received them and the materials were later in possession of a person who misused them." United States v. Hall, 632 F.2d 500 (5th Cir.1980); United States v. Indelicato, 611 F.2d 376, 381 (1st Cir.1979). From a review of the record, we hold that the Government has met this burden.