Outlook 2003 Cached Exchange Mode vs. Mailbox Cleanup Wizard - Mailbox SIzes


I am the Email Admininstrator for a company with a single Exchange 2003 SP2 server that houses approximately 300 mailboxes on it; our clients access their email with Outlook 2003 from their desktops.

A number of our users have Cached Exchange Mode loaded in their Outlook profiles.
We normally set a mailbox cap in Active Directory to force our users to keep their mailboxes under control; however, a growing confusion is occurring regarding apparent discrepancies between the folder sizes as reported in the Mailbox Cleanup Wizard; i.e., the folder sizes differ between the local folders and the server folders (which I suppose is to be expected, though I'm not sure why); the bigger confusion, however, appears to be which set of folder sizes the user should "go" by in determining which folders should be pared back via archiving and/or deleting of data - the local folder sizes or the server folder sizes, in light of the fact that the 2 are synchronizing with each other.  Logic would suggest the server-side size of the mailbox would be triggering the mailbox size warnings, but I'm not sure that Outlook isn't reporting information back to the Exchange Server that might be launching the warning messages based on the local file data sizes.  I just would like to be sure so that I am not leading my users astray on this.

Could someone provide me with a brief explanation or point me to a possible source of information on this?  I've been searching around but haven't found anything that addresses this issue.   Please advise; thanks.
Who is Participating?
MATTHEW_LConnect With a Mentor Commented:
I would assume you could use any of the Microsoft Tools relating to PST on an OST.  I could be wrong.  I see no reason to really do anything with on OST.  You can delete it and reopen Outlook and let it regenerate which may clean it up a bit.  There really isn't any real need to do mainteance on it though.
First off, the server side folder sizes are going to be what matters for mailbox size, mailbox manager policies etc.  The reason that you end up with some differences is the following:

When you run in cached mode, the local workstation has an OST file that mail is stored in.  Because this file is being built on the workstation and things are being deleted from it, added etc, you will wind up with slack space in the file.  The local size is the size that is being taken up in the OST file.  The server size is the actual size that is in the Exchange database.  Although, the server size may not even be the actual size in the Exchange database due to things like single instance storage where only one copy of a message is stored and pointers are placed to that one copy etc.

Hope this helps a bit.

nmorris510Author Commented:
Thanks for the quick response, Matthew!

That makes sense; I didn't realize that .OST files behaved in a similar fashion to the way Exchange's DB files do in terms of "slack" space!  Is it possible to "defrag" an .OST file?  Would you even want to?  I wonder. . .
nmorris510Author Commented:
I agree that it's probably not a good idea to do anything to the .OST files.  I'll tell my users to go by the information reported from the server for folder sizes.

Thanks again, Matthew for your help; much appreciated.
No problem, good luck.
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

All Courses

From novice to tech pro — start learning today.