Exchange mailbox size and perfomance

Posted on 2008-11-07
Last Modified: 2012-05-05
What is the limit to individual mailboxes, or is there one, I have set the database to max at 75 gig (currenty priv.edb at 29gig). I have one user using 14gig (36,000 email plus), next smallest is 5gig. 12 users in all (lawyers mostly) Exchange perfomance is really getting bad. Is the user using 14gig causing perfomance issue? Dell PE server with 4gig mem, P4 3.0 dual , gigabit network, plenty of raid disk space, 120 gig plus availabe. Should I defrag? Should I set limits, if so to what size? I have been trying to get them to archive. Any suggestions?
Question by:mddenton
    LVL 16

    Expert Comment

    Hi mddenton,

    "There are no inherent size limits on individual mailboxes.  The main factors that limit mailbox size, practically speaking, are available disk space, backup and restore times, Service Level Agreements, and Outlook performance."

    "It's not the size of the mailbox that impacts performance - it is the number of items in the folder or folders that are being accessed on the server.  In particular, performance is largely influenced by the number of items in the most commonly used folders: Calendar, Contacts, Inbox, and Sent Item folder."

    If you are running in Cached-Mode, (the default mode for Outlook 2003), then client performance can be an issue.  One thing you should do is keep your OST files (the local data cache) free of fragments.  There is a nice little tool called CONTIG on for this purpose (

    "Try to keep no more than about 2500 - 5000 messages in any of the critical path folders.  The critical path folders are the Calendar, Contacts, Inbox, and Sent Item folder. Ideally, keep the Inbox, Contacts and Calendar to 1000 or less.  Other folders, particularly custom folders created by the user, can handle having larger numbers of items without having a broad impact on the user experience."

    Rather create archive folders for the users to store old, not often accessed mail.

    LVL 6

    Expert Comment

    by:Leon Teale
    my suggestion is not try get them to archive but make them archive!!

    set up their archive to archive mail over 6 months old..and just add that .pst file (archived emails) to the inbox so they can still view them with out it lagging up or echange ;)

    also i think windows can set a defualt for 200mb
    but weather you say a gig each..i dunno, depends how many users you have..but even though they have a limit it doesnt mean they wont get any emails..just gotta archive em :)

    also set a rule so if you do set a limit (so dependds on the limit size) make a rule to make outlook archive all the emails every, 2 weeks or every month

    - Hex

    Author Comment

    I have cache mode turned off. If one user has 34,000 items between inbox, sent, and deleted items, will that effect over-all performance or just that users performance? Here is a look at the mailboxes
                                                                    size                   messages
                       CTHLEGAL\1                     14,349,275         34,002          11/7/2008  3:46 AM            
          CTHLEGAL\2       5,152,950      24,910      11/7/2008  3:51 AM            
          CTHLEGAL\3       3,731,011      20,678      11/7/2008  1:00 AM            
          CTHLEGAL\ 4                       2,673,568         6,364      1/7/2008  1:00 AM
          CTHLEGAL\5                           2,254,598      8,280      11/7/2008  3:49 AM            
          CTHLEGAL\6        2,167,646      8,283      11/7/2008  3:54 AM            
          CTHLEGAL\7       1,763,954      11,741      11/7/2008  3:49 AM            
          CTHLEGAL\8       1,543,713      6,994      11/7/2008  1:00 AM
    LVL 6

    Assisted Solution

    by:Leon Teale
    if you effectivly reduces the amount it takes up on the exchange server and increase performance :)
    LVL 16

    Accepted Solution

    One user's going to influence all performance.

    Author Closing Comment

    Thanks for all information.

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