Title 18, U.S.C., Sec. 1708, makes it a Federal crime or offense for anyone to possess stolen mail matter with knowledge that it had been stolen.

A person can be found guilty of that offense only if all of the following facts are proved beyond a reasonable doubt:

First: That the letter or mail matter described in the indictment was stolen from an authorized depository for mail matter;

Second: That the person thereafter had such mail matter in his possession, as charged; and

Third: That the person possessed such mail matter willfully and with knowledge that it had been stolen.