I haven't heard of any issues in co-existance with SP1 and SP3 together. A list of known issues is already published at http://technet.microsoft.com/en-us/library/ff607233%28EXCHG.80%29.aspx
Hi,We have Exchange 2007 Enterprise Edition with SP1 running in three sites. We have CCR cluster for Mailbox server role in every site. We have 2 CAS/HT server in every site and one public folder server in every site.We want to upgrade SP1 to SP3 now. We are planning to do one complete site at a time every weekend. Now question is if we do One site at a time in one week, then one site will have all servers on SP3 and other sites will have all servers on SP1. Will there be any issue if we have this kind of coexistence in Exchange environment.Thanks,Amit Kapoor
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