How "suspicious" does someone have to be in order for the cops to care?

Mail theft is not a police matter. It’s a federal crime. I’d suggest contacting your local post office to ask how to report incidents like that.

I really can’t imagine a postal empoyee rushing out to your house to tackle an offender caught in the act, so I don’t know how that’s supposed to work.

Well, obviously was not expecting an urgent response. I used that as an example, because to me that is suspicious but I was basically told it was not. So it made me think, if the cops find that normal, what is not?

I’m wondering if the police would think that possibly the person had permission, like if the family were away and asked someone else to go pick up their mail, or maybe the police assumed that the lady was one who lived there? I don’t know if they know who lives in every house. I am guessing they don’t.