[X-Newbies] Problem driving me insane!!!

[Jane]

Folks, really. There has got to be something I can do about the fact 
that my parents are getting each other's emails.

My Mom's account on Comcast, is secondary and my Dad is getting her 
email even when I do not send to both! I have checked the Comcast prefs 
with a tech and they told me there was nothing set to send both from 
there, so it must be in my Mail.app.

I do not mind but who knows, we might want to have SOME secrets from 
Dad!

They are using 10.3.8 and on Mail.app those are the only two emails 
configured.

I am going there again today to see what in the prefs could be causing 
this!