Hello everybody, my first post here

I've 'inherited' a mail system at work that is like this..

We have a web server in a hosting centre - it's also running sendmail. Mail sent to our domain is forwarded by sendmail to an Exchange box sitting in my office. When we send out mail, it goes directly from our Exchange box wherever it is going.

What I would like to do is have sendmail restrict the mail it forwards to a "permitted" list - currently everything is forwarded. Ideally i'd like sendmail to "throw away" mail which is not to somebody in the permitted list - I dont know if that's possible or even advisable. What I do want to do is limit the mail forwarded to Exchange.

Our Exchange box was under RNDR attack, but i've fixed that now.

Also, any comment on how our MX records, reverse lookup etc should be configured for the above set up would be mighty fine too.

Any advice appreciated. Thanks.