Updated: Oct 25, 2018
You can now work offline in Gmail - access your email even when you don’t have any internet access.
Your G Suite Administrator needs to enable "Gmail Web Offline" from the Admin Console for this to work.
From Gmail click the Gear icon and then click Settings
Click Offline from the settings menu
Click Enable offline mail
Select Sync Settings - you can select to keep 7, 30 or 90 days of emails offline
Select Download attachments if you want to keep attachments offline
Select Security and decide what happens with your offline emails when you sign out of your account
If you want offline content to be erased for all users when they sign out of their account, tick the ‘Force deletion of offline data’ on log out of Google account box.