Read, write and delete Gmail messages while offline.
If you are on an airplane or anywhere without Internet access you can still read, write and delete messages in Gmail while offline. Here’s how.
You must use the Chrome browser and have Gmail open in a single tab. From within Settings Click Offline then Enable offline mail. Choose to store emails locally on your device from the last 7, 30 or 90 days. Attachments are included, but Spam and trash are not stored.
When you compose messages offline, they are held in the Outbox. When you reconnect to the Internet the emails are sent and other changes are synced.
This Gmail setting gives you the flexibility to be productive when you are disconnected.