Increase microsoft outlook support for mail box more than 100GB

Niraj Shah 1 Reputation point
2021-11-04T06:41:49.67+00:00

My mailbox size is more than 100GB where outlook is supporting only 50GB. Now My mail sync through google exhcange is stopped. I have tried IMAP config but same issue.

Outlook | Windows | Classic Outlook for Windows | For business
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  1. Faery Fu-MSFT 19,751 Reputation points Moderator
    2021-11-05T09:20:25.677+00:00

    Hi @Niraj Shah ,

    Based on your description, are you referring to the size limit of the data files in the Outlook client?
    Did you encounter any specific error message?

    If you meant the size limit of Outlook data files, as far as I know, in Outlook 2010, 2013, 2016, 2019 and Microsoft 365, this limit is set to 50GB.

    Based on my search, you can increase the limit via the registry to manage the Outlook data files size.
    Important: Follow the following steps carefully. Serious problems might occur if you modify the registry incorrectly. Before you modify it, back up the registry for restoration in case problems occur.

    To modify the registry, here is an document for reference: https://www.msoutlook.info/question/large-exchange-mailboxes-and-the-ost-file-size-limit
    Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

    Step 1: Press ‘Windows’ and ‘R’ keys together to open the Run dialog box
    Step 2: In the Run dialog box, type registry and press Enter
    Expand the registry key due to your Outlook version:
    146799-expand.png

    Step 3: Create the following 2 new DWORD values.
    146800-create.png
    146834-dword.png
    In addition, I also found a document which introduces several ways to clean up items in the mailbox and how to manually compact the OST file after deleting items.
    If you have an Exchange or IMAP account, it is recommended to modify the offline settings to reduce the offline emails.
    File> Account Settings> Account Settings>select your account>Change> move the Sync Slider below: mail to keep offline.


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