How do I manage and reduce Exchange mailbox sizes?

Your Exchange quota includes all your email, attachments, calendaring data, task items, and more. We strongly recommend that you manage your quota by deleting items you do not need and clear out the deleted items weekly. Your Exchange mailbox grows as you create and receive items. When you delete items, the size of the Outlook Data File (.pst and .ost) file might not decrease in proportion to the data that you deleted. There are several ways to manage your mailbox and reduce the size of the data file.

Current Quota Limits

Mailbox Size Cannot Send Cannot Receive
5GB 5.25GB 5.5GB

This means that the mailbox limit (calendars, reminders and etc. take up space too) is 5 gigabytes. At 5.25 gigabytes you cannot send any new messages and at 5.5 gigabytes you cannot receive any mail. 5GB is a LOT of email however any messages with attachments will take up by far the most space. One of the best tips is to NOT keep attachments in your mailbox. For messages you sent it is very likely to file you attached is still in its original location, you do not need to keep a copy in your mailbox. For messages you received see “Removing attachments from an email and keeping the email” below.

Checking mailbox usage

In order to start cleaning up your mailbox you need to know where you stand. Here are some methods of finding your current mailbox size.

  • Outlook Web App - Log in to Outlook Web App (OWA) then hover your mouse over the top folder of your mailbox, displaying your name. A graph will display your quota usage and will contain a caption letting you know how much space you are using.
  • Outlook 2010 / 2013 - Click on the File tab, click Info, then your quota usage info will appear in the Mailbox Cleanup section.
  • Outlook 2011 for Mac - Click Outlook then Preferences then General in the top menu bar. Uncheck the box Hide On My Computer folders. Right-click on the gray MIT header in the Mail Folders list. This counts the usage on all folders. Click Folder Properties then, click on the Storage tab.
  • Entourage 2008 - Control click on the Exchange Icon, then Select Folder properties, then Select Storage.
  • Outlook 2007 - Go to the Tools menu, then Mailbox Cleanup, click View Mailbox Size, then click on Server Data to find out your quota usage on the email server.
  • In several versions of Outlook if you right-click on the top level of the mailbox (usually labeled as your email address at the top of your list of folders in Outlook), and choose “Properties” or “Data file properties” you will get a dialog window and one of the buttons will be labeled “Folder Size.” This properties dialog is available for any individual folder also.

Removing attachments from an email and keeping the email

Sometimes you will be sent an email with very large attachments. While there may be plenty of space on your hard drive (or server) the attachment can cause your Exchange Mailbox to grow in size very quickly, but there's an easy solution.

  • Right click the attachment that you want to save and choose 'Save As'.
  • If there are multiple attachments, go to File, Save Attachments, Save All Attachments to save them all to your hard drive.
  • Once saved to your hard drive, right click the attachment again and select 'Remove'.
  • The file is removed from your email, but is saved to your hard drive.

Using personal folders

Another highly effective method to keep your Exchange mailbox size to a manageable level is to move non-critical email out of your Exchange Mailbox and into your Personal Folders. While email residing in your mailbox is stored on the server, email that are saved on your Personal Folders are kept on your computer.

An IMPORTANT NOTE here is that ANY files saved to your local computer are not protected by daily backup. You need to take steps to manually copy these and ANY important files to a backed-up location (i.e. a network folder) or personal flash (thumb) drive to protect them from loss.

To create your Personal Folders, follow these simple steps:

  1. From your Outlook session, click on the menu Tools and select Email Accounts.
  2. Under Email click on View or change existing email accounts and click Next.
  3. Click on New Outlook Data File and choose Office Outlook Personal Folders File (.pst) and click OK.
  4. Select the file name and destination and click the OK button. The default location is usually difficult to find. Be sure to select a location you know, such as the Desktop or the My Documents folder. You can also choose a network folder, but keep in mind this mail would only be available when you are connected to the network.
  5. From the Create Microsoft Personal Folders dialogue window, you can select the Name to appear in your outlook session.
  6. Choose No Encryption.
  7. Do not set a password, then click OK to finish. If you choose to set a password, keep in mind that there is no way to reset this password if you cannot remember the password the mail is lost.

You are now ready to sort and file away emails in this newly created Personal Folder which is visible in the Folder List (usually the left column of the Outlook window).

Setting up Auto-Archive in Outlook to reduce mailbox size

In order to automatically reduce the size of your mailbox, you can active an Auto-Archive feature to handle this for you. This feature automatically downloads and saves emails onto your local hard drive into its own Archive folder.

The auto-archive tools vary slightly between versions of Outlook. Search Google or contact someone in the IT department for details for your version of Outlook.

Additional Tips for Managing Mailbox Size

  • Empty the “Deleted Items” folder regularly. Outlook can be configure to “Empty the Trash” every time it shuts down.
  • Delete very old messages. 99% of message are irrelevant after a very short period, why do you have 3 year old mail? IF you find you do have a number of seemingly very old items that you know you need to keep, create a special folder, properly labeled, in your mailbox.
  • As mentioned above; Do not keep attachments in your mailbox. This goes for received AND sent messages.
  • Do not use your mailbox as a to-do list, use a to-do list. I know many people find it very convenient to use their mailbox as an action-list or to-do list and I understand why. In fact it is often a suggested productivity tip. In practice though it is less than ideal. Important items quickly float down the list as new mail arrives. Using a dedicated method (even a simple paper list) is more effective because you get the items reinforced when you copy them to the list and the list … well, is less likely to get buried under new items.
Last modified:: 2016/03/19 16:03