The only time I ever open my husband's mail is:

1. If it's a package addressed to both of us.

2. If I have reason to believe it contains food that may need to go straight in the fridge. His boss occasionally sends cheese.

I did open a package addressed to him this week that I knew contained something for me too.

On the other hand, there is a problem in this marriage. Likely he is trying to spare her stress, but it's not going to work in the long term.