Outlook cannot download emails exceeding 50G

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Hello, there is a mailbox in Exchange Server 2016 that uses about 150G of space (Exchange does not limit the mailbox space size). When we install Outlook 2019 on computer A, we need to download 150G of emails, but when the download reaches 40G, Outlook will no longer receive emails. I changed the regedit on computer A and can receive emails with a capacity of 200G, but Outlook still no longer accepts emails. Is there a way to solve the problem of Outlook not being able to receive emails?

Windows Server 2019
Windows Server 2019
A Microsoft server operating system that supports enterprise-level management updated to data storage.
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  1. Wesley Li-MSFT 4,346 Reputation points Microsoft Vendor


    Outlook has a limit on the size of the offline Outlook Data File (.ost), which is used for IMAP, Microsoft 365, and Outlook.com accounts. When the .ost file reaches this limit, you may experience performance issues and you might not be able to add more data to the .ost file.

    Here are some steps you can take to resolve this issue:

    Archive Old Emails: Archiving old emails can help reduce the size of your mailbox and free up space. You can set up automatic archiving in Outlook to move older items to an archive folder.

    Compact the PST File: Compacting the PST file can help reduce its size. To do this, right-click the PST file in Outlook, select ‘Data File Properties’, click ‘Advanced’, and then click ‘Compact Now’.

    Delete Unwanted Emails: Deleting unwanted emails, emptying your junk email folder, and deleting items from other folders can also help reduce the size of your mailbox.

    Increase the Outlook Size Limit via Registry: You can increase the size limit of both the .pst and the .ost files in the Windows registry. However, increasing the file size limit should be done with caution as it can impact the performance of Outlook and your system.

    Use Mailbox Cleanup tool: Outlook has a built-in Mailbox Cleanup tool that can help you manage the size of your mailbox. You can find it under File > Tools > Mailbox Cleanup.

    Remember to always back up your data before making any major changes to your system. This can help prevent data loss in case something goes wrong during the process.

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