If your Gmail mails are important, you must backup them frequently. Previously, you have to follow many steps to backup Gmail account. But now, it became easy with selecting few options and backing up the mails.
For this method, visit takeout.google.com/settings/takeout and sign in with your Google Account username and password. After logging in, you will be shown a list of all Google services linked with that account and a grey color box for that service. Data of these services can be downloaded on to your computer.
In that, find 'Mail' and click on the grey button next to mail. If you see a green box with a tick symbol, you are ready to go to next step. If you want to backup few mails, click on the drop down icon next to tick box and select Labels options to select the labels.
After that, click on the next button and you will be asked to select the file type, Archive size and delivery method. Choose .zip as file type and choose the maximum archive size and delivery method of your choice and click on 'Create Archive' button. That's it! You backed up your Gmail account.
In this process, you can backup your mails to Google Drive or Dropbox or to OneDrive or get a link to download the backup on to your computer through an email. With Gmail mails, you can backup data from other Google services linked with your account.
Please note archives created through this process may expire. Visit support.google.com/accounts/answer/3024190 for more info.
So, this is one of many ways to backup Gmail emails. You can backup through software, through cloud based services and through POP download. This method is a simple backup of all your mails.