If you are using SMTP connectors, then one domain at a time will work. If you are using a smarthost on your 2003 virtual servers, then you'll have to do them all at once.
Regards, Michael B. Smith Consultant and Exchange MVP http://TheEssentialExchange.com From: Chris Pohlschneider [mailto:chris.pohlschnei...@hollowayusa.com] Sent: Monday, August 02, 2010 2:38 PM To: MS-Exchange Admin Issues Subject: Sharing SMTP Name Space Issue Hello, I am trying to configure mail flow from one Exchange 2003 SP2 Organization that contains two Exchange servers to an Exchange 2010 Server Organization. Both of these organizations are in different forests and we are migrating away from 2003 and putting everyone on 2010. There is a trust relationship between the two forests and DNS naming is resolving correctly between the two forests through the trust. My question is do we need to configure the SMTP name space sharing for the entire Exchange 2003 Organization at the same time or can we do just one e-mail domain at a time in the 2003 Organization? Chris Pohlschneider Holloway Sportswear Network Administrator chris.pohlschnei...@hollowayusa.com<mailto:chris.pohlschnei...@hollowayusa.com> 937-494-2559