Login to Webmail with your current password
Go to Preferences -> Accounts -> Primary Account Settings and
Go to ‘Applications’ above Password Recovery Account Settings:
Click the ‘Add Application Code’ button
Enter a name for your device in the ‘Application Name:’ field
Click on the ‘Next’ button
Make a note of the Application Passcode
When using your device for the first time, you will need to enter this passcode to sign in to Webmail, without needing to use two-step authentication.
Click on the ‘Close’ button
The device has now been added
If you loose your device and want to remove the device passcode
Click on the device name
Click the ‘Revoke Code’ button to remove your device’s passcode.