We are currently in the process of migrating from exchange 2007 to 2010. We are working on the SSL cert we will need for our environment. Our current SSL cert for our 2007 servers is expiring shortly and the question was raised whether we can renew that cert with one SSL provider while for the 2010 servers generate a new SSL cert with a different provider. I dont see why this would not work as the 2007 servers will be gone in less than 6 months and we only want to renew that for one year. Our 2010 servers we will purchase for 3 years. If someone could confirm this would work without any issues it would be appreciated.