When using the Microsoft Outlook e-mail client, the size of the mailbox and local PST files is constantly growing. In this article, we will show you the basic ways to cleanup and reduce the size of Outlook mailbox.
To find out the current mailbox size in Outlook 2016/2013/2010, right-click on your e-mail account in the left folder tree and select the Data File Properties menu item.
Then click on the Folder Size button. As you can see, the overall size of the mailbox has appeared, as well as the size of each mailbox folder. In our example, total mailbox size (including subfolders) is about 2.6 GB.
If your Outlook .pst personal folder files (Outlook Data Files) are connected in Outlook, you can see the size of each folder in its properties the same way.
The built-in Outlook mailbox cleanup tools are located in the following menu: File > Info > Mailbox Setting > Tools. Three options are available:
- Mailbox Cleanup;
- Empty Deleted Items Folder;
- Clean Up Old Items.
Select Mailbox Cleanup and a window will appear offering several ways to cleanup your mailbox. Below we will look on how the Outlook cleanup tools work.
Archiving Older Emails in Outlook
You can automatically archive old emails in Outlook. Go to File > Options > Advanced. Click on the AutoArchive Settings button in the AutoArchive section.
Turn on the Run AutoArchive every xx days option and specify the auto-archive frequently.
You can automatically move old items to a separate PST file or delete them.
When archiving, mailbox items are deleted from your Outlook mailbox (they are not taken into account in its size) and most often they are moved to the archive file on your hard drive. Please note, that this archive is not accessible remotely. If the archive contains information that is important to you, do not forget to periodically back it up.
In order to start archiving manually, select File > Info > Tools > Mailbox Cleanup > AutoArchive.
Save and Remove Attachments in Outlook
If emails with large attachments arrive in your mailbox, you can save them to a local drive on your computer, to the OneDrive or other cloud storage to reduce total mailbox size.
- Find in Outlook and open the e-mail with a large file attachment;
- Right click on the attachment and select Save All Attachments;
- Specify the folder in which you want to place the attachment file and click Save;
- Now you can remove the attachment from the original email item. Click on the attachment and select Remove.
Empty the Deleted Items folder in Outlook
When you delete any email item in Outlook, it is not actually deleted, but is transferred to the Deleted Items folder. Therefore, if you accidentally delete an item from your Outlook mailbox, you can restore it from the Deleted items (Trash) folder.
Hint. To permanently delete the email item from the Outlook mailbox or from a PST file without transferring it to the Deleted Items folder, select the item and press Shift + Delete.
You can cleanup the contents of the Deleted Items folder manually by right-clicking on the folder and selecting Empty folder.
You can automatically clear removed items from the Deleted Items folder when you close Outlook. To do this, go to the File > Options > Advanced menu and enable the Empty Deleted Items folders when exiting Outlook option in the “Outlook start and exit” section.
Now, when you close Outlook, the following dialog box appears:
Do you want to permanently delete everything in the “Deleted Items” folder for all accounts.
How to Shrink a PST/OST File in Outlook with Compact Feature?
Outlook also has an Outlook Data Files compression feature (.pst and .ost). To compress your data file with data, select File > Account Settings > Account Settings > select Data Files tab. Select pst or ost file you want to shrink and in the next window click Compact Now. This procedure will clear unused areas in the data file (“white space”) and the data file size will be reduced.
It is recommended to compress the mailbox after each cleanup.
Hint. Outlook performs automatic file compaction if the white space in the data file is more than 20% of total file size.