Mail App

My daughter is receiving MY emails as well as her own. I do NOT get hers - which is not an issue, we both do NOT want to each other to see such personal emails anyway.

I.e.:-

I send or receive an email, they appear on her MacBook Pro (Mojave).

But not any of her other Apple devices) plus,

HER emails do not appear on my MacBook Air (nor any of my other apple devices)

Why is this and how can we 'fix' it - prevent MY emails ending up on My Daughter's MacBook Pro??