Hello,
The application is not supporting taking snapshot and remving that.
But try esx 5.1 build 1483097 there is improvement in the snapshot.
Understanding Exchange 2010 Virtualization: Exchange 2010 Help
Some hypervisors include features for taking snapshots of virtual machines. Virtual machine snapshots capture the state of a virtual machine while it's running. This feature enables you to take multiple snapshots of a virtual machine and then revert the virtual machine to any of the previous states by applying a snapshot to the virtual machine. However, virtual machine snapshots aren't application aware, and using them can have unintended and unexpected consequences for a server application that maintains state data, such as Exchange. As a result, making virtual machine snapshots of an Exchange guest virtual machine isn't supported.
Best regards,
Yoni Shperling