Exchange File Extensions

*.edb - Exchange Database file
E:\database\Accounts\Accounts.edb

*.chk - checkpoint file - keeps track of which transactions have moved from the transaction logs to the database - so in the event of the being an interuption of those transaction logs being moved to the database, if anything happens the checkpoint file can be used to refernece.
E:\log\Accounts\E04.chk

*.log - 2 different types - the current transaction log e.g. E00.log, but once this gets to 1mb it is re-created again and is renamed to e.g. E00000000001.log
E:\log\Accounts

*.jrs - Used if the server gets to the end of its storage space and has no more room to wright any more information into transaction logs (There should be 2 of these logs just for an emergency like that)
E:\log\Accounts\E04res00001.jrs

tmp.edb - Tempory workspace to store data before written to main *.edb database
not present in 2010 - i think its now E:\database\Accounts\Accounts.edb.IRS.RAW