If you wish to take a backup of your emails then you can definitely do so via a third-party client. Firstly, please set up your email account on a third-party client. To know how to do so, please click here.
Once your account is set up on a third-party client, you may refer to the steps mentioned below according to the client you have set up your account on.
1. Launch Thunderbird
2. Select your inbox or the folder from which you wish to export the emails
3. Select the emails you wish to export or press Ctrl + A to select all the emails
4. Click on the menu button, navigate to Save as and select the option of File
5. Select the folder where the emails should be saved and click on Save
That's it! You'd be having access to all the emails in the selected folder. For any further assistance with this, please write to us at email@example.com, we'll be happy to help you