We have an exec which has asked for ALL his email to be pulled out of the email archive tool and into his mailbox. When I say exec, I mean the guy that runs the company level! My team lead has requsted the job be action and half way through the restore his mailbox is already up to 17GB. He has 160,000+ items in the mailbox (filtered away in folders by date and month so not all in his inbox). Outlook 2010 is running against Exchange 2010 in ONLINE mode due to Citrix being in use here. Can people advise what sort of problems to look out for with mailboxes this size, or is Exchange 2010 OK for indexing mailboxes of that size GB and item wise?

The real issues with mailbox size of which I am aware are (1) the number of items in a folder, (2) the number of folders, and (3) cached mode. (1) If there are a lot of items in a folder, say more than 1,000 to 5,000, then it can take a long time for Outlook (in cached mode) or Exchange (in online mode) to render the view when the user clicks on the folder. So it's especially ugly when there are a lot of items in the Inbox. (2) If there are a lot of folders, you're going to be overwhelmed by warnings in the event log. (3) It's a daunting thought that a user would be synchronizing 25GB or more of offline folders between the server and his Outlook client. Think of how long that would take if he had to create a new OST for some reason.Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

Thanks Ed. We won't be using offline sync as Outlook runs in online mode due to Citrix so thankfully a 30GB mailbox won't need to sync!! One thing is that his folders are neatly away from his inbox and the general default Outlook folders are all clean meaning no more than 5000 items in a folder. He has a folder for every year since 2002 with a month for each year within each. Unless somoene else chimes in saying "You're screwed!" I suppose I will just have to let it grow and see what happens!

This is a perfect use of the online archive mailbox feature of Exchange 2010.Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."