When you use Google Workspace Sync for Microsoft Outlook (GWSMO), your mail is stored both remotely in the cloud and locally in a PST mailbox file on your computer. The cloud can hold up to 30 GB of mail, which is more than you'd typically need to keep on your computer. The amount of mail you can store locally is limited by Microsoft Outlook's mailbox size.

What happens if I run out of space?

As you run out of space locally, older mail is removed from your computer and replaced with newer messages. If you’re searching for messages in Outlook, you’ll only find messages that are stored locally on your computer. However, you can search for these messages using the Gmail web interface.

Most people do fine with a local limit of 1 GB, but if you want to store more mail locally, you must increase your mailbox size. We recommend you use GWSMO to do so. This option is discussed below.

Alternatively, you or your administrator can set the mailbox size limit using a Windows registry key. For details, go to Set mailbox size. You can use either the registry key or the GWSMO option to set the mailbox size, but not both.

Use GWSMO to set Outlook's mailbox size (recommended)

1. Click GWSMO  in your Microsoft Windows taskbar notification area.

   If you can't find the icon, it might be hidden in the overflow area. To view all icons, click the up arrow on the taskbar.

2. Click Set mailbox size limit.
3. Select a mailbox size—1 GB, 2 GB, 4 GB, or Unlimited.

   Depending on your computer, a larger mailbox size can degrade performance.

4. Click OK.