Enable IMAP in Gmail
Set up as an IMAP account, Gmail in Outlook for Mac receives and sends mail, and it accesses all your old Gmail messages. The first step is enabling IMAP in Gmail:
Select the Settings icon and then choose Settings. Go to the Forwarding and POP/IMAP tab. Select Enable IMAP and then select Save changes.
Set Up Gmail in Outlook
Next, open Outlook for Mac and follow these steps:
Select Outlook > Preferences > Accounts. In Outlook for Mac 2011, go to Tools > Accounts. On the Accounts screen, select the plus sign (+) in the lower-left corner, and then select New Account. Enter your Gmail address and password where prompted. If you have 2-step authentication enabled for Gmail, create and use an application password specific for Outlook for Mac. Select Allow. Select Open Microsoft Outlook in the window that appears. Wait as Outlook completes the process. Then, select Done.
What Gmail in Outlook for Mac Lets You Do and Access
Messages that have been assigned a label (or more than one) in Gmail on the web appear in folders in Outlook for Mac. Likewise, if you copy a message in Outlook to a folder, it appears under the corresponding label in Gmail. When you move a message, it is removed from the corresponding label (or the inbox) in Gmail.
Under Junk E-mail, you have access to your Gmail Spam label. Drafts, deleted, and sent messages are in the Outlook for Mac Drafts, Deleted Items, and Sent Items folders, respectively.