UNIX and Linux Applications

Hello there,

First of all I tell you that this is my first postfix installation so please be patient...

I have following scenario:

fetchmail --> postfix --> amavis-new --> postfix --> exchange 2010.
Everything -except exchange ;-)- runs on an opensuse 12.1 box.

Now, I have a list of domains entirely managed and hosted here so I have resolved everything using the transport file (do.main.name smtp:[exchange.ser.ver]) and the entries in the main.cf file (mydestination= $myhostname, localhost.$mydomain, localhost, $mydomain, do.main.one, do.main.two, domain.diffi.cult).

So far so good, everything seems to work for the "simple" domains.

Now, I have got one user with an address at domain.diffi.cult and this domain is not hosted by me. This user has a mailbox on the exchange server and everything is working fine on that side.

How can I configure postfix to deliver the mails for myuser@domain.diffi.cult locally and all the others @domain.diffi.cult to the internet?

Just a further clarification...
I am the owner of those "simple-to-manage" domains. All the managed domains are regularly polled with fetchmail, scanned for spam/viruses with amavis and then sent to the users mailboxes on exchange. Those domains can be easily managed locally because all user of those domains also have an exchange mailbox.

The user @ the difficult domain also has an exchange mailbox and has to send and receive mails using outlook/exchange. His address @ that domain must continue being used because it's an old known address.

Within Exchange everything works fine: if he sends mails to the other users/domains it works, if the other users/domains send mails to him it works.

The problem is that if I declare in postfix that domain as local, postfix tries to deliver all the mails addressed to users @ the difficult domain locally (to the exchange server) and that is wrong because they don't belong to the local organization thus -of course- aren't managed locally.

I succeeded in having a working config based on sendmail, but now I have to switch to postfix...

Any clue anybody?

Thanks
Luca