Exchange 2010 / Outlook 2010 Mailbox size limits

I definitely don't claim to be an expert in Exchange by any means so here are my few simple questions:

Can you increase the max size of users' mailboxes to larger than 50GB?
Does doing so circumvent the 50GB max file size limit of Outlook?

Does allowing access to different mailboxes combine the file size on the local machine?
      for example:    if John accesses his own 25GB mailbox and also has access to Jill's 25GB mailbox in his outlook, does that combine and reach the 50GB outlook limit?

I think that's mostly it for now.

thanks EE!

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Hypercat (Deb)Commented:
You can set a maximum size limit in Exchange for user mailboxes per user or globally.  There's no restriction on the max size limit that I'm aware of. However, I would not set it that high.  A bunch of 50GB mailboxes could seriously impact performance, particularly in Outlook and even, IMO, on the server (although I'm no expert on managing hardware resources for Exchange).

As to size limits in Outlook, this is only impacted if you're using PSTs or OSTs to store the contents of the Exchange mailbox.  The 50GB limit is hardcoded in the registry:

That said, again I would not recommend having anyone running a mailbox from a PST or OST that is that large.  It would seriously impact performance, not so much due to the size of the mailbox itself but due to the number of items in the mailbox, indexing requirements, etc.

The real answer to managing mailbox and PST/OST sizes is archiving.  If you can take advantage of the archiving features of Exchange, users can still have access to all of that data but without overloading their main mailbox.
Hypercat (Deb)Commented:
Taking a look at this article, it implies, at least, that you cannot allow a PST/OST larger than 50GB:
ophirbrokeAuthor Commented:
HC,  thanks for the quick response.

There are only 3 mailboxes in this setup, so I'm not too terribly concerned about impact on hardware.

That said,  I agree that archiving is the ideal answer.  However my main concern with that is that I need an archiving solution that still allows multiple users to access the archived items.

My understanding of exchange archiving is that you can break off a chunk of your exchange mailbox and archive it, but it stores it locally in a PST - which you only have access to locally.

This environment  has 1 user with a 40GB mailbox that everyone else in the office accesses constantly. Which is why I asked if adding mailboxes combines the size of the local OST file.  vs. the other option of - each mailbox you add gets its own local OST file.
It appears that everyone has 1 OST file that's combining the sizes of the mailboxes they're accessing

anyone know the answer to that?

thanks again
Hypercat (Deb)Commented:
Archiving - what you're thinking of is Outlook archiving, which creates local PST files.  Exchange archiving stores archived email in a separate mailbox store which in most respects operates exactly the same way as the main mailbox store.  The major "gotcha" with Exchange archiving is that in order to view your archive mailbox other than through OWA, you need the Professional Plus or Enterprise version of Microsoft Office.  That can be pricey, but we've found that users mostly don't actually look at their archive mailboxes that often and when they do they don't mind opening OWA to do so.

And, somewhat contrarily to what I said in my previous post, if you only have 3 mailboxes on your Exchange server, I would not be using cached mode.  I would let users connect directly to the Exchange server to open their mailboxes, and that way you don't need to worry about accumulating large OST files on the local workstations.  Unless the users are in remote offices, this would probably work better overall. Or you could do a "hybrid" sort of Outlook profile setup where they use an OST for their own mailbox but not for the one that everyone shares:
Will SzymkowskiSenior Solution ArchitectCommented:
I asked if adding mailboxes combines the size of the local OST file.  vs. the other option of - each mailbox you add gets its own local OST file.
It appears that everyone has 1 OST file that's combining the sizes of the mailboxes they're accessing

anyone know the answer to that?

When you are connecting multiple mailboxes to an Outlook profile it will use whatever is set in the Outlook client. If you are using Cached Exchange Mode, then EVERY mailbox you attach to your Outlook client will pull down its own OST files. OST files do not get merged, so you will have one for each mailbox.

Personally if you are going to connect to mailboxes this large, I would recommend either using Outlook in Online mode only (this does put more load on the Exchange server with a consistent connection), or you can have the user/s log directly into the mailbox using OWA.


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