1) As a safeguard, create a folder where to move unwanted log files before actually deleting them.
2) Run eseutil.exe on the checkpoint file to find the latest log file to keep in the mailbox folder.
"C:\Program Files\microsoft\exchange server\v14\bin\eseutil.exe" /MK "e:\mailbox\users\e04.chk"
3) In the example above we locate the filename E040008FAA6.log. and note the modified date.
4) Move all .log files prior to this modified date to another folder.
5) Reboot the server and check whether everything mounts properly.
6) If all OK delete the files. If not, revert them to the old location.