Enable IMAP for Gmail Inbox

Step 1. Go to Gmail inbox and click the settings icon on the top right corner.

gmail_inbox

Step 2. Click "See all settings" button.

gmail_quick_settings

Step 3. Select "Forwarding and POP/IMAP" tab in the settings page.

gmail_imap_settings

Step 4. Choose "Enable IMAP" option under IMAP access section and click the "Save Chabges" button.

gmail_enable_imap