How to Reduce Mailbox Size in Outlook

Is your Outlook mailbox full? Are you getting weekly or even daily notifications and pop-ups indicating to reduce the Microsoft Outlook mailbox size immediately? If yes, then you must understand that it can eat up your considerable amount of time cleaning up your Outlook mailbox. However, if you know some better tricks, then you can save your valuable time when reducing the size of your Outlook mailbox.

Six Useful Methods to Reduce mailbox size in MS Outlook

Try these methods for quick but easy processes to deal with keeping your mailbox smaller and simpler to work.

1. Mailbox Cleanup

The first thing you need to do is to open the Mailbox Cleanup tool. You can use the tool by performing the below steps:

  1. Select File > Info > Cleanup Tools > Mailbox Cleanup.
  2. First, select the View Mailbox Size option. It will help you know the current size of your mailbox and the majority of the subfolders. This is a good approach to the target, which folders are the greatest supporters of your large mailbox so you can clean up these first.
  3. When linking to Exchange, you’ll see the Local Data and Server Data tabs.
  4. Select the Local Data tab. The cleanup changes you make will automatically happen on the server also.
  5. Next, select the alternatives to find older or larger items, which you can remove directly from the results to clean up the Outlook mailbox size.
  6. Depending on your archive settings, you can also go for the Auto Archive option.
  7. Finally, check the size of the Deleted Items folder and Empty the folder if you need particular choices details below. If available, one choice is to view and delete various versions of items in our mailbox.

2. Move Messages to Your Personal Folders

In case you’re connected from Exchange, you can use this another approach to decrease the Outlook mailbox size. In this approach, you need to move Outlook items to your Personal Folders. This option may not be accessible to you as many associations have moved far from supporting Personal Folders.

However, if you can see this option then must undertake this step because the messages you move to Personal Folders are never again checked in the size of your mailbox. The Personal Folders document (outlook.pst) is put away on your local hard drive and isn’t open remotely. You should back up this file to prevent losing these Outlook items if your PC goes down or crashed. If you are running an independent version of Outlook, your email, calendar, assignments, and notes are altogether put away in the outlook.pst file, which has a size limit of 50GB (Outlook 2010 and 2013).

3. Archive Older Messages

Another valuable support step is to archive your Outlook organizers occasionally. If you are accessing Outlook from Exchange, you will be unable to change archive choices as documenting is regularly controlled by system administrators or an outsider program.

However, if you are not connected via Exchange, you can perform the below steps to configure Archive settings in your Outlook.

  1. Setup your archive preferences under the Info > Cleanup Tools > Archive option.
  2. The archive.pst file can be made and updated at any location on your PC, more often than not your local hard drive. Archived things are removed from your Outlook mailbox size and moved to the archive file based on the settings you decide.

Similarly, as with the Personal Folders document, your archived things are not open remotely; the file should be backed up all the time.

4. Empty Deleted Items

Regularly clean up your deleted items via naturally emptying the Deleted Items folder when you exit Outlook.

Perform the below steps to empty deleted items folders:

  1. Select File > Options > Advanced tab.
  2. In the Outlook star and leave option, check Empty Deleted Items folder while leaving Outlook.
  3. Click the OK button.

You can also manually empty the Deleted Items folder if you do not want to configure automatic deletion.

Perform the below steps to manually delete emails from the Deleted items folder:

  1. Open the Deleted Items folders.
  2. Select emails that you want to delete and click the Delete key on your keyboard.
  3. You can also right-click the Deleted Items folder and select the Empty Folder option on the shortcut menu.


Once the emails are deleted from the Deleted Items folder, you cannot recover them back. If you feel sure that you need to erase a message permanently, you can avoid the Deleted Items folder by squeezing [Shift] + [Delete] for a selected thing rather than simply the [Delete] key. At that point, just confirm the delete procedure.

5. Save and Remove Attachments

Attachments in email messages are responsible for vast space used to your Outlook mailbox size. Depending upon the email correspondence, one choice is to save the attachments of mail and after then remove them from the original email.

Perform the below steps to remove attachments from emails:

  1. Open the email.
  2. Right-click the attachment and after that choose the Save All Attachments option.
  3. Or, select Actions from the Message tab. Then choose Other Actions > Save All Attachments.
  4. Next, browse the folder where you need to save the file(s) and choose to save option.
  5. Once you have saved the attachment, remove the message if it doesn’t need to be held. If you need to keep the message, you can remove attachments from the email by right-clicking them and selecting the Remove option.

6. Split PST

This option works well in case the size of your Outlook PST file has grown to the size making Outlook slow while creating the chances of the PST damage. Also, if the size of your Outlook PST does not reduce even after executing the above-listed processes, then you are left with splitting your huge PST file into small files. You cannot do it manually so the tools like Split PST tool can be helpful to overcome the oversized PST file issues. And, the best thing to know here is, the new PST files can be imported anytime in Outlook as per the requirement. The Split PST tool is recommended as it does not make changes to the original PST file so there are no chances of data loss. You get the best quality with this tool. The data remain as is and accessible with any version of Outlook including Outlook 365.

How to repair large PST files that are inaccessible?

If you’re unable to access a large PST file, then you need to repair it using the Outlook PST repair tool.  It can repair even large-sized PST file and save it into smaller and manageable files, without compromising its data integrity.


So, these are some of the methods that you can use to reduce the size of your mailbox in Outlook. These steps can save you plenty of time because if you start finding and deleting unwanted emails one by one, you will end up wasting your time, and at the end, you may not see good results.

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