Get IT Done: Control mailbox size in Exchange

Method for controlling mailbox size in Exchange

As you add users to your Exchange server and as they start sending more and more messages, you’ll probably notice that it takes longer to back up the server each night. You may also notice that you’re quickly running out of drive space and have to add hard drives to your servers. One easy solution to this problem is to restrict the size of your users’ mailboxes. In this Daily Feature, I’ll show you how.

Getting started
I suggest you proceed slowly with setting up mailbox size controls. I recently had to debug an implementation that had been set up with all the limits activated. The company couldn’t figure out why certain authorized users couldn’t send out e-mails of any size.

The first thing to check is the current sizes of your users’ mailboxes. This will give you an idea of the current situation so you can develop a plan to control mailbox size.

Start Exchange Administrator, go into the Size container for your Exchange server, and click on the server’s icon to expand it. Continue to expand the information until you see the Private Information Store and Mailbox Resources below it.

In the right pane, each mailbox is listed with the number of items and total size. Depending on the screen resolution of your administrative workstation, you may see several columns at the same time. If you click on the Total K column, you can sort mailboxes from smallest to largest, top to bottom.

If you have a lot of mailboxes, you may need to get a printout to develop a plan for handling mailbox growth. Unfortunately, you can’t do this within Exchange Administrator. But you can export the information to a file that you can print out using Excel. Select Save Windows Content from the File menu. Enter a filename for the mailbox listing and click Save. Accept the default file type of .CSV to make it easier to import into Excel and print the reports. Open the file in Excel and print it out as you would any normal spreadsheet.

After you print and review the initial report, you may want to visit the workstations of the users who have the largest mailboxes and help them clean up their mailboxes. At a minimum, this cleanup involves clearing out the Sent and Deleted Items folders if they use Outlook. You should also help them decide which messages are most important and remove nonessential messages. Make sure that they delete messages with attachments if they’re finished with them. Otherwise, make sure they’ve saved the attachments to their hard drives.

Deciding on how to control mailbox size
Once you have the mailboxes cleaned up, you can decide how to best implement mailbox size control to minimize day-to-day administration. There are three control levels you can implement:
  • The information store
  • The mailbox
  • Connectors

The best way to think of this is to separate the controls into two categories—the information store and mailboxes in one group and the connectors in another group. The reason is that whatever limits or allowances you grant at the information store and mailbox level are ignored by the connectors because connectors have their own limits.

For the purposes of this Daily Feature, we will be working with just the Internet Mail Service connector. While there’s more than one way to manage the size of your Exchange mailboxes, I suggest setting limits that will cover the greatest number of users. The easiest way to do this is by using the limits available at the Private Information Store level and then granting exceptions as needed at the individual mailbox level.

To set these limits, go to Exchange Administrator. Click on Private Information Store and then File Properties. In the Storage Limits area, you’ll see that you have three ways of controlling the mailbox size:
  • Issue Warning
  • Prohibit Send
  • Prohibit Send And Receive

If you want to issue a warning when a mailbox grows larger than 15 MB in size, enter 15000 in the input field to the right of the Issue Warning line and select the Issue Warning check box. Enabling this option doesn’t control mailbox size but will send a friendly reminder to each user whose mailbox is close to the maximum size you specify.

The Prohibit Send option allows you to prevent users from sending e-mails when their mailboxes exceed the size you specify. The user can still receive e-mail, but won’t be able to send e-mail until the mailbox size falls below the setting. If you use this option, you should set this option with a size larger than that used for the Issue Warning option that you just enabled.

The final option, Prohibit Send And Receive, is not one that I think you should enable. It prevents the user from getting e-mail when his or her e-mail box gets too big. Enabling this option may cause users to miss important e-mail.

Creating exceptions to the rules
What do you do if you have some users, like your CEO, for whom you want to create exceptions? In Exchange Administrator, double-click the Recipients container for your mail server. You’ll see a listing of the users on this server. Double-click on the mailbox for which you want to create the exceptions.

When the properties screen appears for that user, click the Limits tab. By default, each mailbox will be automatically set to the same limits as those you specified on the Information Store properties screen. Look for the area labeled Information Store Storage Limits. The Use Information Store Defaults check box will be selected. If you want a user to have no restrictions placed on their mailbox size, uncheck this box.

If you want more restrictive or permissive mailbox limits enabled for a particular user, uncheck the Use Information Store Defaults box and then check each of the options you want to enable for the user. Set the appropriate values and click OK.

There’s an additional option on this screen that wasn’t available to you on the Information Store properties screen. This is the ability to control the size of messages that can be sent and received by this mailbox. You should usually be able to accomplish your objective of controlling the overall mailbox size without having to limit message sizes.

Controlling the message size at a connector
You can also control the size of a mailbox at the connector level. Although this uses a little more brute force than the options that were available at the Information Store we just finished looking at, it’s a tool that should be considered. Click the Connections container in Exchange Administrator and then double-click the Internet Mail Service connector.

On the Internet Mail Service properties screen, click the General tab and you’ll see a Message Size area. By clicking on the Maximum (K) selection and entering a value in the Maximum (K) input field, you can control how large a message can be and still pass into or leave your Exchange server. Keep in mind that this option affects everyone and cannot be overridden at the mailbox level.

In this Daily Feature, I’ve shown you how to get control over a mail server that needs more and more drive space or takes forever to back up. All you have to do is apply limits to your users’ mailboxes. As with any change to your Exchange server, you may find that after enabling this new feature you have to spend a little more time administering Exchange than before. After you find the optimum settings for mailbox sizes, however, you’ll be glad you did.
The authors and editors have taken care in preparation of the content contained herein but make no expressed or implied warranty of any kind and assume no responsibility for errors or omissions. No liability is assumed for any damages. Always have a verified backup before making any changes.

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