That will work, I have done just that on . With a few caveats.
1 - Backup the Information store and test the backup.
2 - The PST files you will be exmerging to can only hold 2gb of data so yopu will need to repeat the process.
Below are the steps I took to clear out our mailboxes including one large mailbox.
Just a run down of what steps, I think, will need to be done when we put the 60 day Recipient Policy into effect. The batch files will be in the Exmerge directory on the d: drive.
.5 – Verify that the E: drive has enough space to hold 2x the current EDB file. Copy the backups to EAS and then delete them to gain the room.
1 - A successful backup of the Exchange Information Stores (******-Mail).
2 – Take the ******-Mail mailboxes offline.
3 - Run ISINTEG_******_Before.bat without errors, warnings are acceptable. There will be about 500 warning messages (See the end of the document for an example). ISINTEG_******_Before.bat has ISINTEG.EXE setup with the needed parameters to check the Information Stores and will run both global tests (ALLFOLDERSTEST and ALLACLTESTS).
4 – WARNING this step is to only be done IF there are errors in the Information Stores! Run eseutil_fix_database.bat and then rerun ISINTEG_******_Before.bat.
5 – Bring the ******-Mail mailboxes back online.
6 – Run Exmerge_******.bat. This is a three-pass process.
The first pass will remove any mail dated between December 31, 1899 and April 1, 2002 from the Deleted Items folder in P*****’s mailbox.
The second pass removes any mail dated between April 2, 2002 and October 1, 2002 from the Deleted Items folder in P****’s mailbox.
The third pass will remove any mail dated between December 31, 1899 and October 1, 2002 from the following folders Sent Items, Deleted Items, and Inbox for all active mailboxes.
7 – Take the ******-Mail mailboxes offline.
8 – Run exmerge.bat, this will do an offline defrag of the Information Stores to reclaim the space freed by the Exmerge. Only run eseutil_fix_database.bat if there is an error while defragging the Information Store.
9 – Run ISINTEG_******_after.bat there should be numerous (over 1000) warning messages (See the end of the document for an example).
10 – Run Isinteg_******-fix.bat to fix the warnings.
11 – Run ISINTEG_******_after1.bat there should be zero warning messages.
12 - Bring the ******-Mail mailboxes back online.
13 – Run a backup of the Exchange Information Stores. Copy the BKF file created here to the EAS server.
14 – Add the recipient policy to the Exchange Server, Schedule when and how often the policy will run, and Start the Management Process. This can be done at any time since the policy will look at the date the data was added to the database not the date the email was received by an email program.