When using DPM 2007 to backup an Exchange 2007 server, you may encounter this:

“DPM encountered a retryable VSS error ID 30112. Details: Unknown Error 0x800423f3“

I have read where this was an issue with Exchange 2007 if the rollup pack is 3 or less. The article looks like it was updated on February 19th, so the problem likely still exists.

Here’s the link to the “fix”.

http://technet.microsoft.com/en-us/library/bb217320.aspx

Basically, you have to restart the Information Store and Exchange Replication services to workaround it.