Just a word of caution for anyone about to import old PST files and EX-Merge Backups alongside their actual Mail Store.
The option that specifies "A message will only be imported if it is not in the archive" is slightly misleading. This actually means the message will not be imported if it has already been imported from a specific location. If the same message is sourced from two different places, ie. a PST file and the Exchange Mailbox Store, it will be imported from both places and you will have duplicated emails and duplicated attachments.
I had many overlapping PST files and ended up with more than 50,000 duplicated emails and attachments, some of which were duplicated more than 10 times. The size of my archive triggered my investigation.
I wiped everything and started again. Complete uninstall and complete removal of all Exclaimer software, settings, users and databases as per the manual. After reinstalling and reconfiguring with an empty database, I planned to import only the Mail Store and leave the PST files until I could work out what to do with them. This time round, almost nothing was imported. OMI had already imported everything from my previous installation and therefore decided not to import anything. OMI must check a flag in the message about to be imported, rather than the database to determine if it should be imported. Checking the database for every message would have a huge hit in performance.
I ran the Store Compressor in Analysis Mode ready to complete the process, thinking my Archive and import had completed successfully after running all night and into the next day. I checked a few older emails to ensure they were in the Archive and realised what had happened.
Started again for the third time with a clean install and selected "Import All Messages" but only from the Mail Store.
Is there likely to be a utility to remove duplicated emails and attachments in the near future?