Mailbox limits with Exchange SP2

Posted on 2010-01-06
Last Modified: 2012-05-08
With Exchange SP2, what kind of problems might occur if you leave the mailbox size to unlimited?  There is plenty of space on the server so that really would not be an issue for a very long time.   Microsoft suggests a certian size limit be setup and I am wondering is there a specific reason other then just to conserver disk space?   What type of problems would occur as these mailbox sizes increase.  

The reason I ask is that I am supporting a company that left the default to unlimited mailbox sizes.  Total of 25 mailboxes.   It has not been an issue but my gut instinct and general best practice is that this eventually can't be good.

Right now I have one user with 5,020,098 KB mailbox size which is excessive.    I have another 2 that are 3 GB or higher and 7 users that are 2 GB or more.     I'm just trying to cover my end by understanding if this could be a problem on the server end eventually.  In the past, Exchange didn't handle this well but that was 8 years ago and a different version.

I've recommend the users to create personal folders and to manage their folders better but it falls on a deaf ear.    Their laptops are high end so the process speed has not been compromised yet when openining Outlook.   If I have to recreate their Outlook profile that sometimes takes a log time.

Again any experience or insight on this issue would be great!
Question by:CAT27
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    Planning Mailbox Store Limits
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    Author Comment

    That is for Exchange 2000 which is not what we are using.  And I understand how to change all of that but thanks for the quick response.  

    I am asking if anyone has personally experienced this unlimited mailbox size to cause any issues in their environment or is this just a suggestion by Microsoft that only has meaning when your disk storage is limited?

    Author Comment

    The Quotas is helpful, thanks for that.    I really don't think I'm going to get to change any of this type of stuff until I have some concrete reasons and that is why I posted this question.   Hopefully someone can help with that.
    LVL 58

    Accepted Solution


    Allowing user mailboxes to grow uncontrollably is a major issue. The mailbox quotas give users an incentive to keep their mailboxes down in size, conserving space on the server.

    You didn't mention which version of Exchange 2003 you are running. However, there is a default database size limit of 18GB in 2003 Standard Edition. This can be raised to a hard maximum of 75GB - and then the database will not grow any larger. You have to make a registry tweak for the size limit to be pushed up to 75GB:

    5GB mailboxes are not really anything large, though. I have a number of Exchange Servers where 20GB mailboxes are not out of the norm. The problem normally comes with the number of items stored per folder in Outlook; Microsoft recommend no more than about 5000 items per folder to ensure Outlook remains stable.

    In most organisations, the main issue is the use of email as a) a long term storage solution and b) another file server. I am frequently reminding businesses - particularly small/medium business owners - that Exchange is a COLLABORATION solution, NOT a file server. If 5GB mailboxes concern you, find out what the users are storing there and advise they move large attachments to a file share someplace else.

    Many of these changes cannot come from IT but must come from a policy implemented by management, so your experience of your work having little effect isn't uncommon either. Unless you forcefully stop people using their mailboxes (by implementing quotas), you won't get people to listen.

    Finally, the use of PST files (Personal Folders) is an incredibly bad idea. I wrote an article here at EE which covers why:'t-use-PST-files.html.


    Author Closing Comment

    tigermatt information wrote a lot of what I already knew but it gave me some thing to show that backs what I've been saying all along.   Until something crazy happens I'm not sure I will win this battle and they will continue to treat mail as a storage.

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