[Exim] Exim web/pop issues

I have exim set up and it was working ... I have no idea what went wrong
on the box...
But now ... exim won't send any email's to pop accounts but it will send
it to any web-based accounts (ie: hushmail.com)

Could this be an issue of hostname has been changed? or the MX records
could have been changed at the isp?

any idea's or leads on this would help...

thanks again.

j