I was recently asked this question similar to this:
How can we search on unmounted EDB files? Are there any API's that I can use to access the mails in unmounted EDB?
There are two answers:
“No” and “It’s a bad idea”.
There is no support for accessing unmounted EDB files. There are no Microsoft APIs for doing this. There are third-party APIs on the web. The format for these files is not really documented and thus is not something you should depend-upon. If you use a third-party application to access an EDB which is mounted, you may cause corruption or potentially take down Exchange. Any API which alters data in an EDB is risking causing corruption. If you choose to still try to read the unmounted EDB file, you should note that you may not get all of the data you are seeking – remember that information may be in the STM file and not the EDB until its data is promoted to the EDB file.
What about recovery of an EDB?
There are some third-party applications which do fixes against an EDB. These are not supported by Microsoft. Remember that Exchange 2000 and 2003 have two data stores and not just one. Information is sync'd between the two based upon need. The process of syncing the data between both databases does cause a performance hit, so only what’s needed is synchronized. Because of this, the EDB file may not (most likely will not) have all the data needed for a full restore. Please read the links below and fully understand how the database files which Exchange is driven off of work together.
In a production environment, nobody should be attempting to repair an EDB file. Thats what backup software is for. Brick-level (item & property) backups are not supported by Microsoft. Exchange is supported with backup software which uses VSS or the older Exchange Backup API. Also remember that Exchange integrates heavily with AD, so AD should always have its data backed-up.
I know that there are a number of third party APIs, backup and recovery programs out there which may work where you have no other path forward. However, such software/APIs should only be used as a last resort. Its best to use supported soltuions - which you know will work now and in the future.
Microsoft Support can assist with recovering data with supported tools. So, if you need to recover data, please contact them.
How about ESE.DLL or anything else people try to use to get at EDB content:
Developers sometimes try to use the ese.dll in order to get at EDB content. It’s clearly spelled-out in MSDN that it’s not supported to do this.
Microsoft support policy for third-party products that modify or extract Exchange database contents
I know that one section of the article indicates that you "might" be able to access the store in a read-only mode but there are some major differences in the different implementations of the ESE engine that can get you into some real problems.
Although this is a documented API and is very similar to ESE used with Exchange, it is not designed for use with Exchange and has limitations/differences that can result in problems with the Exchange store. I also suspect that the ESE functionality is going to be newer than the ESENT functionality since ESE/Exchange is continuing to be updated. It would not be surprised if any ESENT based apps that you get to work, fail with future releases since we have no commitment to ensure that ESENT works with Exchange.
The third-party tools and APIs mentioned above may use ese.dll to accomplish what they are doing. However, it’s not supported or recommended by Microsoft at all.
Here is some homework if you wish to know more:
Exchange Storage Architecture
Exchange Transactions and the Exchange Database Overview
About: Exchange APIs to backup and restore data
Please note (11/4/2013): In the past 20 days there have been eight comment postings by entities portraying themselves as separate companies with Exchange recovery tools which directly read Exchange’s EDB files. This is a lot since I’ve only seen two such comment posts on since I wrote this article five years ago. Further, two those comments were posted early last Saturday morning for different products which seem to do the same thing. I can only assume that were all posted by people trying to spread malicious software. So, I’m going to need to approve all comments on this post from here on.