Postfix issue

[David Southwell]

Hi

Could anyone tell me what entry I should make in postfix configuration files 
to bounce mails directed to root at mydomain that emanate from a source outside 
my local network.

Sorry to ask the question here but postfix users mailing list is currently 
rejecting mails from servers on a dynamic ip address - so I cannot get 
through to ask a question there.

Thanks

David