"Go to the post office! I'm sure her picture's up!" what does it mean?

[Joeyy]

Monica: This woman's got my life, I should get to see who she is.
Rachel: Go to the post office! I'm sure her picture's up!

---Friends S01E21

 

[GoesStation]

American post offices used to have notice boards displaying "wanted" posters; that is, flyers with pictures of people suspected of serious federal crimes. Rachel thinks "this woman" is a criminal.

 

[bubbha]

Don't American post offices still do this?

 

[GoesStation]

Don't American post offices still do this?

My local post office stopped a few years ago. I miss the Wanted notices.