I found a post from last year that indicated there was no limit to the number of pst files that could be connected to an Outlook 2007 mailbox.  However, I have two users, one with 43 pst files and another with 82 pst files attached to their Outlook 2007 profile (don't ask me why, I'm fighting that battle separately right now).  In both cases at any time there will be certain pst files they can't open: they get the standard Outlook error that the set of folders could not be expanded. Which pst files can not be opened varies so it doesn't appear to be a problem with the pst files being corrupted: one time files 1 and 73 may open and files 65 and 80 won't and the next time the user opens Outlook 65 and 80 my open but 1 and 73 won't.  Is there some sort of limit on the number of folders Outlook can open regardless of whether it is a pst or something else?TBrennan

On Thu, 19 May 2011 17:25:56 +0000, TPBrennan wrote: >I found a post from last year that indicated there was no limit to the number of pst files that could be connected to an Outlook 2007 mailbox. However, I have two users, one with 43 pst files and another with 82 pst files attached to their Outlook 2007 profile (don't ask me why, I'm fighting that battle separately right now). In both cases at any time there will be certain pst files they can't open: they get the standard Outlook error that the set of folders could not be expanded. Which pst files can not be opened varies so it doesn't appear to be a problem with the pst files being corrupted: one time files 1 and 73 may open and files 65 and 80 won't and the next time the user opens Outlook 65 and 80 my open but 1 and 73 won't. Is there some sort of limit on the number of folders Outlook can open regardless of whether it is a pst or something else? This is a question better asked in a forum for Outlook. The Exchange server has no part in the management of the PST files. --- Rich Matheisen MCSE+I, Exchange MVP --- Rich Matheisen MCSE+I, Exchange MVP

Hi TBrennan, You can also see this blog: But I Really Need To Open 500 PSTs! http://blogs.msdn.com/b/stephen_griffin/archive/2009/06/09/but-i-really-need-to-open-500-psts.aspx Frank Wang TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Excellent reference! Thanks.TBrennan