exchange server 2003

The event ID mentioned above will show you the free space that is currently in your DB, but if you lower the retention period on the mailbox / mailstore to 0 days for both, then after 24 hours, the Event ID will show an awful lot more (assuming your users have deleted plenty of data over the last 30 days - which is the default retention period).

http://www.msexchange.org/tutorials/mf022.html

So  event 1221 is going to be the amount we will get back if we run Eseutil command?

Correct, because the offline defrag will recover the logical freespace. My advise would be to get your users to clean up their mailboxes, including deleted items prior to the defrag.

Read the following article, note how much available disk space you need (can be on any partition even a USB disk) and it also gives a guide as to how long it might take.

http://technet.microsoft.com/en-us/library/bb123761(v=exchg.65).aspx

If your question is that you are running out of disk space - then running eseutil /d will require you to have 110% of the mailstore size in free disk space on the server you run the tool on, otherwise it won't work.

If you don't have 110% free disk space on any volume on the server, then you can run the tool on another server (without Exchange) that has 110% of the mailstore size in free space:

http://support.microsoft.com/kb/244525

So - if your store is 50Gb (.EDB + .STM), then you will need 55Gb of free space to run eseutil happily.

space is not a problem, you don't have to run this tool on the exchange server. Yo can run where ever you have the free room. But all i am lloking for is to see how much white space i am going to get back if i ran this tool.

In that case as we said, look for event 1221 on your exchange server.

Johan_strange's first comment in this question answers the amount of white space you will recover.  It is detailed in Event ID 1221 in the Application Event logs.

thanks