Suppose you are working on a computer using the internet, suddenly you found that there is no internet connection. It is a very common thing. But you have to check your emails for your work. Without the internet you cannot read emails.
Now I am going to tell you How to Read, Compose or Even send Emails in Gmail while there is no internet connection (Offline). You can send emails. Whenever your computer gets connected to the internet all mails will be sent automatically.
So use this trick you need Google Chrome Browser. If you don't have it, Download it from the below link.
Step 1:
After installing Google Chrome, You have to login into your Gmail account.
Then you have to go    Offline Gmail Setup Page  .
Now on the top-right of that page, click on   + ADD TO CHROME  

Step 2:
Now a new window will open. In that window click on " Add "

Step 3:
Now click on   LAUNCH APP  

Step 4:
A new tab will open. On that page Select " Allow offline mail" and then click on " Continue ".

That's all. Your offline Gmail is successfully activated. You are almost done. Now whenever you lost your internet connection, then to access your gmail account just go to the below link in your Google Chrome Browser.
To send email, just click on Compose, after composing mail Click on Send as link normal procedure to send emails.
When your computer gets connected to the internet email will be sent automatically.