We setup exchange 2010 sp1 but we noticed that users who have outlook client 2007 and 2010 get prompted about ssl certificate. One is the external for the owa and then requests for the internal CAS server. These are people who haven't been migrated yet to exchange 2010, they are still on exchange 2003. I noticed even those that have been migrated, some were prompted but it went away. Not sure what is going on with this. Has anyone run into this issue.