To set the duplicate‑handling option in RME, navigate to Tools > Settings and go to the Duplicates tab.
The first option is the simplest one. RME does not consider what already exists in the production Inbox and simply copies everything it finds in the backup. There is no burden other than the copy operation.
Options 2 to 4 use a different approach.
For each message found in the backup, RME retrieves its PR_SEARCH_KEY property and does a search (!) in a target folder. If a duplicate is found, RME applies its 'remove duplicates' logic (compares creation times, replaces if it's newer, etc - depends on the option selected).
The question then arises: "What affects the recovery speed?"
1. Which 'duplicate removal' option is selected (1 is faster, 2,3,4 are slower);
2. Number of messages in target folders (a big number of folders with fewer messages works faster than one huge Inbox);
3. Speed of MAPI connection between RME (Outlook) machine and target Exchange Server.
If, for example, better performance is achieved when restoring to another mailbox, it could be explained by having fewer messages in that mailbox and/or by a different folder structure.
