Set a local mailbox size

G Suite Sync for Microsoft Outlook

When you use G Suite Sync for Microsoft® Outlook® (GSSMO), your mail is stored both remotely in the cloud, and locally in a personal storage table (PST) mailbox file on your computer. The cloud can hold up to 30 GB of mail (or more), which is a lot more than you'd typically want to keep on your computer. The amount of mail stored locally is instead limited by Microsoft Outlook's mailbox size.

If you run out of space locally, older mail is removed from your computer and replaced with newer messages. All messages remain available in your Gmail account on the web. Most people do fine with a local limit of 1 GB. But to store more mail locally, you can choose a larger mailbox size.

Note: You can only search locally stored emails in Outlook. If your Gmail inbox size exceeds your local mailbox size, emails excluded from your local mailbox do not appear in Outlook search results. You can still search for these emails using the Gmail web interface.

Set Outlook's mailbox size with GSSMO (Recommended)

The GSSMO tool can help you adjust Outlook's mailbox size.

  1. Click the GSSMO icon in your Windows® taskbar.
    1. The GSSMO icon appears in your taskbar, typically next to the clock. From here you can access the GSSMO settings.
    2. If you don't see the GSSMO icon, it might be automatically hidden by Windows. Click the small white up arrow on the taskbar to show all icons.
    3. Note: The GSSMO icon will only appear if GSSMO is running.
  2. Choose Set mailbox size limit. (This command isn't available if your mailbox limit is set using a Windows Registry key.)
  3. Select a mailbox size from the dialog that opens. Your options are 1 GB, 2 GB, 4 GB, or Unlimited. Note that depending on your computer, a larger size might degrade performance when searching and indexing.

    Why is a size option not available?If your local PST file already exceeds one of these sizes, the option is no longer available in the Set Mailbox Size dialog. That is, once you select a larger size and your PST file grows to that size, you can't go back.

    Why is my PST file larger than the size limit? It's possible your PST file may exceed the size limit. This depends on your Outlook set up. Consult your Microsoft documentation to see how to configure the size limit for PST files in Outlook. You can also reduce a local PST file, which helps compact the file's size.

    Does the Unlimited size option really mean unlimited? No. By default, Outlook limits the size of a local PST file to 20 GB (for Outlook 2007) or 50 GB (for Outlook 2010, 2013, 2016, or 2019). So, if you choose the Unlimited mailbox size in GSSMO, your PST file won't exceed 20 GB or 50 GB. To increase the limit of your PST file, consult your Microsoft documentation. (Note that if you choose the Unlimited mailbox size in GSSMO and your PST file grows larger than your default Outlook limit, you might encounter sync errors. In addition, large PST files can create performance problems.)

    Does setting the mailbox size impact all my Outlook accounts? No. Settings Outlook's mailbox size only affects the primary mailbox account. To apply a different mailbox size limit to your delegated accounts, you must set the mailbox size limit using a Windows Registry key. For more information, see Limit mailbox size.

Set Outlook's mailbox size with a Windows Registry key (Advanced)

The Windows Registry is used to store information, settings, options, and other values for Windows software and hardware. The data is structured in a tree format and the configuration settings exist in registry keys and registry values.
You or your administrator can set the mailbox size limit using a Windows Registry key. For details, see Configure options through the registry. Note that you can use either the registry key or the Set mailbox size limit option, but not both.
Consult your Microsoft documentation for more information on the Windows Registry.

Reduce a PST file

You can try using Outlook to compact a local PST file, in which case a smaller mailbox size limit might become available. Consult your Microsoft documentation to see how to reduce the size of your mailbox and Outlook Data File.

Change a PST file location with GSSMO

You or your administrator can update the folder location of a local PST file.

  1. Click the GSSMO icon in your Windows taskbar.

    For help with locating the icon, see the instructions above.

  2. Choose Modify PST/logs folder paths.
  3. Use PST Folder Path to update the location of the PST folder.

Note: If you modify the PST folder path, the new location only applies to PST files associated with profiles created after the path change.

For details about GSSMO log folders, see Locations of log files.

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