Aug 14, 2018 - Before you connect to your Gmail account from Outlook on the web, or add a Gmail account to Outlook, you need to prepare your Gmail account.
When you are using a Gmail account over IMAP in Outlook, you’ll also automatically get an Gmail or Google Mail folder containing all the “system folders” of Gmail itself. To break yourself out of this additional subfolder and have all these folders listed directly under your mailbox in Outlook, you can set a root folder for your Gmail IMAP account. However, this has an effect on any Labels that you might use in Gmail. Luckily, there is a workaround for this as well.