If you are a regular user of Gmail on a laptop, you normally need an internet connection to use it. However, Gmail has a little known Offline option. This allows you to continue to read and compose emails without an internet connection. When you finish composing and send the email, the email goes to a newly visible Outbox folder that stores your new emails until you regain internet access. Also, all your recent archived emails will now be accessible to you.Read More.
Setting the Offline option
If you want to be able to use Gmail on your next flight or for any time you lose wi-fi access, you must enable it while you still have an internet connection. Click the gear icon and choose Settings. Then choose the Offline option. Click the box Enable Offline Mail. Select the Keep Offline Data On my Computer option and click the Save Change button.
Gmail on other devices
This Offline option works with Windows PCs. Other implementations of Gmail work differently. For example, Gmail on iPhone always allows you to see archived emails without an internet connection because these emails are stored on your phone. Checking the iPhone storage option in settings may show you a hundred or so MB of documents and data used by your Gmail app. When you try to send an email in airplane mode, the email will sit and spin in your Sent folder until you regain internet access, at which point it will send.
Getting access to older emails
Whichever device you use to access your Gmail, you have probably noticed that you cannot scroll through older archived emails. However, those emails are still saved and available on Google's servers and you can reach an individual email using the top search box. Unfortunately, you do need to remember a phrase to identify that email.