Hi there,
Thank you for posting here. I'm JohnJr and I'll be assisting you with this technical issue.
Based on my test, once the mails are archive to a local .pst file, these mails are nowhere to find on the server.
Regarding the checkpoint file you mentioned, it is a small (8KB) which contains information about which transactions in the log file have already been flushed to the disk. The checkpoint file points to the next un-flushed transaction in the log series. In other words every transaction before (or older) than the checkpoint we know has already been written to the database file. The checkpoint file is only ever used during Soft Recovery and is in fact not essential.
These files cannot help recover the archived and deleted mails.
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More Info:
Exchange Transaction Logs and Checkpoint Files
http://msdn.microsoft.com/en-us/library/ms986143(EXCHG.65).aspx==================
Best Regards,
JohnJr
MCSE 2003