I haven’t done much with Enterprise Vault and processing of Exchange journal mailboxes in a while. I still like to gather information on it though. A question arose the other day about the registry key NoOfMsgsPerJournalPass, in the following article :
The key is no longer valid in Enterprise Vault 9 and onwards, instead you set the value on the task itself :
As the online help says, you probably won’t get a lot of mileage from changing this from the default of 1000. Historically people have changed this (with the registry key) temporarily if they have had a journal backlog.