VirtualHosting conflicts in Sendmail

hi,
im using my linux box to host some sites (virtualhosts in apache).
My ISP has the primary and secondary dns.my box is a cache-only dns.

There are 2 problems:
ONE, is with the virtualhosting in sendmail:
Whenever mail is sent to one of the virtual addresses eg: info@domain2.com, the mail goes to an inbox for a user@domain1.com and to the user info who is meant to receive the mail for domain2.com.

TWO,
There was some erratic behaviour that i couldn't explain at all.My linux box acts as the web proxy in an office lan.one of the users, received in his yahoo inbox, a mail message that was destined for one of the virtually hosted addresses on the mail server.
What could be wrong?

Hope i've been clear enough...
thanx in advance