postfix smarthost to relay in same domain

[Paul Howarth]

str tux wrote:
>>if you mean, your old mailserver should forward outgoing mails to the new
>>server see here:
>>
>>http://www.postfix.org/BASIC_CONFIGURATION_README.html
>>
>>see section  "What delivery method: direct or indirect"
>>
>>hth
>>Roger
> 
> 
> Thanks Roger,
> 
> relayhost is properly configured and relaying works except as i
> desired. limme explain further:
> 
> domino server users:
> john at mydomain.com
> peter at mydomain.com
> 
> postfix server users:
> jane at mydomain.com
> laine at mydomain.com
> 
> i have no issue in my domino server as anything not local user to the
> domino server it is forwarded to my postfix server.
> 
> the problem now occurs in postfix.
> if i put mydestination and relayhost as:
> mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
> relayhost = [mail.mydomain.com]
> 
> i'm not able to send to john at mydomain.com
> 
> if i set mydestination and relayhost as:
> mydestination = $myhostname, localhost.$mydomain, localhost
> relayhost = [mail.mydomain.com]
> 
> i'm able to send to john at mydomain.com but not able to receive email
> within any users in postfix server.
> 
> in exim as i'm little bit familiar, you can set a transport smarthost
> and you can set to check first any local users in the local server and
> if it is not available it will be forwarded to the relayhost
> (smarthost).
> 
> how to achive same thing in postfix?

In an arrangement like this, what would happen if someone sent a mail to 
a user that was not local to either server (e,g, due to a mistyped 
username)? It looks like a recipe for a mail loop to me.

Paul.