Help! Mail to 'localhost' not staying local CORRECTION

[V.I.Victor]

>I don't think your hosts file is correct, unless you are telling me you own 
>the domain athome.net.  You need to use a domain name you own or one that 
>is not in use.

OK.  

No I don't own athome.net.  BUT I've been using it for years without problems -- until today! As I said, the hosts file is it's always been.

It seems that "localhost" just isn't local any more.

I'm trying to figure what's changed and what I should do about it.

So far, I've stopped all the internal mail to localhost.