Monitor & Maintain the Size of Your Outlook Mailbox

Staff at libraries in our system learned this spring we need to keep our Outlook mailboxes under 1 gigabite (1 GB) in size.  (The amount of email stored on our Exchange server had grown enough that reducing each staffperson's mailbox quota could save backup space and improve the efficiency of our email server.)

For some staff, getting below 1 GB wasn't a problem.  But others (like me) needed to pare down our mailboxes in a big way, so we set about archiving messages and saving & removing attachments to get under the 1GB mark.  I'd met my goal by the deadline, but after a month passed — and more attachment-heavy emails arrived — I thought I might be close to bumping up against my limit again.  I checked my Outlook's mailbox size, and sure enough — I realized I'd need to regularly monitor my mailbox size to ensure I wouldn't go over my quota.

Here's what I did, and you can too:

  1. Open Outlook (2010 or 2013; if you use 2007 click Tools-> Mailbox Cleanup instead)
  2. Click on the File tab.
  3. If the Info section doesn't open by default, click on it to see your Account Information.
  4. Look at the Mailbox Cleanup section, and note the storage space remaining.
  5. Click the Cleanup Tools button.
  6. At the Cleanup Tools dropdown menu choose Mailbox Cleanup.
  7. In the Mailbox Cleanup window that opens up, click the View Mailbox Size button.
  8. The Folder Size Window will open, take a few seconds to calculate, and display an overview of your mailbox folders and their sizes.
  9. Use the Folder Size Server Data window's scrollbar to discover the biggest folders. (Note that Calendar entries, Notes, and Tasks also take up space in your Outlook account.)
  10. Take notice of the biggest folders — these are the folders you'll want to inspect for messages that are overly-large. 
  11. Click the Outlook Home tab to get back to your inbox.  Then open those big folders and look for email messages with large attachments that can be saved on your hard drive & removed (right-click the attachment and choose Remove Attachment; get details at this Ides post), and also choose old messages that can be archived in a data file outside of Outlook.
    Tip: make sure you have the Size column visible in your folder, and click on the column header (see details at this Ides post) to sort messages by size (largest at the top) to choose the messages that are in most need of attention.

By using this method I discovered large email messages I'd missed seeing the first time I whittled down my mailbox; I cleaned them up and earned some breathing-space in my email quota.  At least until the next PowerPoint or Excel attachment arrives, that is.  :-)

Tip: When you close Outlook for the day, use the File tab and Exit button method — that way you'll see where your quota stands at the close of each workday.

Contact Pete Hodge if you have any questions about your Outlook account.

Note: get info on email records retention policies at the Declutter Your Desk and Organize Your Office workshop resources page.

Use Outlook Web Access/App (OWA) instead of Outlook?  Watch this brief video that demonstrates how you can maintain your mailbox too:

And get more tips for controlling the size of your mailbox at a previous Ides post.