Re: Postfix question

>> declare this server in mynetworks,
>> adjust filters for mynetworks, reject the rest :)
>
> Ok, but postfix default accepts mail for $mydestination. If I remove
> this, will postfix receive any mail?

 From the manual (mydestination):
The list of domains that are delivered via the $local_transport mail  
delivery transport. By default this is the Postfix local(8) delivery  
agent which looks up all recipients in /etc/passwd and /etc/aliases.  
The SMTP server validates recipient addresses with  
$local_recipient_maps and rejects non-existent recipients.

So only list domains here where you do local deliveries for. If the  
server is only a relay, leave this empty or just the servername itself.

If you describe your setup and needs for us, a better advice might surface :)