Take Heed of Mailbox Quotas in Exchange 2010

Storage has come a long way from the days when disk space was selling for $700,000 a gigabyte, but that doesn’t mean you can ignore storage quotas for in your Exchange infrastructure.

No matter what the size of a mailbox is, there will always be some users who will exceed it unless you keep a leash on them. You can do that through storage quotas.

Storage quotas are size limits you can impose on your users’ mailboxes. They can be configured through the Exchange Management Console or Shell and the properties option for the database for a group of mailboxes.

Ordinarily, you’d want to set a quota for an entire mailbox database, but you can set a quota for individual mailboxes, too. That can only be done through the Console or shell, though, and it will override the quotas set at the database level.

You can access the properties to a database through the Console. On the Console tree, you navigate to Organization Configuration > Mailbox. In the result pane that appears, select a database to configure from the Database Management tab.

Under the database name, an action pane will appear. Click Properties to display a series of tabs for configuring the database. The Limits tab is used to set quota levels.

You can set up to three quotas for a mailbox. Each triggers a warning or a warning and an action when a user exceeds the quota.

For example, let’s say your maximum mailbox size is 2GB. You may want to set your first quota at 1700MB. (The form fields on the limits screen are calibrated for megabytes.) That means when a user’s email storage exceeds 1.7GB, they will receive a warning, “Your mailbox is almost full” and the advice “Please reduce your mailbox size. Delete any items you don’t need from your mailbox and empty your Deleted Items.”

A second quota could be set at 1800MB. By default, that warning will prohibit the user from sending any more mail until they clean up their act. If you set a second quota, you must make sure your first quota is greater than 50 percent of it, otherwise the first warning won’t be triggered.

Finally, you may want to set a third quota at 1900MB. Along with warning a user that their mailbox is about to max out, breaking this quota will cut off both sending and receiving mail by the user.

You don’t have to set all three quota levels. You may want to set up the first quota, for instance. If you do that, however, the user will receive a message that says, “Your mailbox is becoming too large. The current size is xxMB.” With all quotas enabled, the warning messages contain a bar graph that shows used and unused mailbox space.

A number of other options are available from the Limits tab, too. For example, you can set the interval at which mailboxes are scanned for compliance with the quotas or set the number of days a mailbox may retain deleted messages.

By setting quotas for your users’ mailboxes, you head off future problems, such as filling up the disk space in the partition that’s home for your mailbox database.

Written by John P Mello Jr

John Mello is a freelance writer who has written about business and technical subjects for more than 25 years. He is frequent contributor to the ECT News Network and his work has appeared in a number of periodicals, including Byte magazine, PC World, Computerworld, CIO magazine and the Boston Globe


  1. Ken W. · April 29, 2012

    This is a very useful feature.

    People tend to allow emails to accumulate without weeding out old ones.
    But different people use emails differently. Others only use text files. Others get heavy attachments extensively. And although attachments can be downloaded and saved elsewhere, others would like to keep old emails for purposes of being able to track down conversations or threads that will be useful for future references.

    Could we set a quota, say 2GB for line staff, 5GB for another group of employees, etc, etc. and to be able to change the quota of one particular person at any particular time?

    This would be another useful feature.

  2. Luke Dean · April 29, 2012

    This is basically what our system administrator in our office does. I find it very useful and effective on the part of the user. Unconsciously, this is helping me organize my email. Once I see that storage quota warning, it forces me to spend some time cleaning and arranging my inbox. Then this is the part where I would realize that I left other important emails unattended. I get to maximize my inbox and other folders once I started to reorganize.

    Another thing I noticed, with the help of the warning, my computer does not hang as I open my mail and I can do my tasks without having to bother to restart.

  3. Owen Lainard · April 30, 2012

    I always support a lower first quota, in this example something like 1400Mb, to get people to actively try and keep their mailboxes a little cleaner without losing any functionality. Then of course, once they hit the upper levels, it’s time to cut their functionality in case they get too bogged down.

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