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 for both the file system and any software that needs to handle files of that size. However, I encountered a case where this limit needed to be increased for Outlook to continue functioning correctly. This required editing the following Windows 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 that’s all.