1. Go to Settings -> Email Preferences
2. Enter your IMAP details as shown below. Note: it is recommend you use an "app password" for this.
3. Save, then click Test
4. If you get any errors while trying to connect your Gmail account, go over each step below:
- Wait for a minute or two and see if you get a "security" warning from google. Say Yes it was me, then try the test again.
- If you never get the security warning then see here for further steps: https://www.inflatableoffice.com/support/knowledge-base/article/gmail-authentication-issues