What is the impact of having both Exchange 2007 SP2 and SP3 on the same organization?

You will have no Impacts as you can co-exist Exchange SP2 and SP3 within the same Organization.MCP, MCSE 2000 , MCSA 2000 ,MCSA 2003 , MCITP , MCTS , MCT

yes they can co-exist. if you are upgrading please upgrade client access servers first then HT and so on.Dhruv

We have one site that is trying to install Windows 2008 R2 with Exchange SP3. Our main site with hosts our external OWA services(outlook anywhere, etc.) has SP2. Can this configuration work?

Hi Claudioji, I would not suggest that exchange 2007 sp2 and sp3 coeistence, it seems some issue with the WEB service proxy and redirect between the CAS in each sites. I would update the exchange 2007 sp2 to sp3 in main site and then deploy the exchange 2007 sp3 in branch site. Regards! Gavin TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Hi Claudioji, I would not suggest that exchange 2007 sp2 and sp3 coeistence, it seems some issue with the WEB service proxy and redirect between the CAS in each sites. I would update the exchange 2007 sp2 to sp3 in main site and then deploy the exchange 2007 sp3 in branch site. Regards! Gavin TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. I agree with Gavin, I wouldn't necessarily 'co-exist' Exchange 2007 SP2 and SP3 version in the same AD Site. SP disparity between AD Sites isn't such an issue as you will usually upgrade at one site at a time. (Take Exchange 2010 co-existence for example and upgrading any Exchange 2007 internet facing sites to SP3). Keep it simple, have all Exchange servers, in the same AD Site at least, at the same SP level. Oliver Oliver Moazzezi | Exchange MVP, MCSA:M, MCITP:Exchange 2010, BA (Hons) Anim | http://www.exchange2010.com | http://www.cobweb.com | http://twitter.com/OliverMoazzezi