How to Increase the Outlook PST File Size Limit

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Microsoft Outlook has a 50 GB size limit, which is excessive and makes it difficult to manage both for the file system and any software handling files of that size. If you need to increase this limit to keep Outlook running properly, you will need to edit the following registry file.

    Outlook 2003: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\11.0\Outlook\PST
    Outlook 2007: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Outlook\PST
    Outlook 2010: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\14.0\Outlook\PST
    Outlook 2013: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\15.0\Outlook\PST
    Outlook 2016: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\16.0\Outlook\PST
    Outlook 2019: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\16.0\Outlook\PST

it can be done with Powershell https://learn.microsoft.com/es-es/powershell/scripting/overview?view=powershell-7.4

before editing, you have to do a backup.

# Specify the path to the registry key you want to back up.
$registryKey = "HKLM:\Software\YourSoftware"

# Specify the path where you want to save the .reg file
$backupFilePath = "C:\Backup\registry_backup.reg"

# Export the registry key from the .reg file
Export-CimInstance -ClassName StdRegProv -Namespace root\default -MethodName ExportKey -Arguments @{
    hDefKey = "HKEY_LOCAL_MACHINE"
    sSubKeyName = $registryKey
    sFileName = $backupFilePath
}

Once the registry is backed up, we can edit it to increase the default PST file size. In my case, I’m going to edit the Outlook 2016 registry.

    HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\16.0\Outlook\PST

Add a new DWORD (32 Bit) Value with the name MaxLargeFileSize Value Data: 102400 Decimal (100GB)

Add a new DWORD (32 Bit) Value with the name WarnLargeFileSize Value Data: 97280 Decimal (95GB)

and done.