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After you make this change, none of the shared folders in the secondary mailbox will be available to you in Outlook when you are working offline. However, all folders in the primary mailbox will still be available to you when you are working offline.
Method 2: Delete large Outlook emails and attachments
Deleting large emails, undoubtedly, is the wisest technique. Rather than randomly deleting large-sized files, you can follow a systematic approach to manage Outlook attachments . The steps are:
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Open Outlook. In the folder list, click Search folder, then select New Search folder.
Scroll down the list and under Organizing Mail, select Large mail. Click Choose under Customize Search Folder.
Specify a size in the ‘Show mail greater than’ box (for example 6000 KB). Click OK to continue.
Click OK again and a folder named ‘Larger Than 6000 KB’ is created under Search Folders. This newly created folder will get updated with the mails of size more than 6000 KB automatically.