It is a known issue of Outlook 2013/2016 connecting via IMAP.

Symptoms:

  • mail isn't populating
  • Sent Items, Outbox, Junk Email folder etc. show up as the subfolders of the Inbox folder.

Until Microsoft releases an update to fix the issue, use the following workaround:

  1. In Outlook 2013/2016, navigate to Home > Info > Account Settings > Account Settings:
    Change account settings
  2. Select the IMAP account and click Change (or double-click the IMAP account name)
  3. Navigate to More Settings > Advanced and enter INBOX in the Root folder path field
  4. Click OK > Next > Finish
    Root folder path

All default folder will show up as top-level ones and mail will start populating to the Inbox folder.