yallo offers you the option to choose between free electronic billing and paper bills sent by mail (CHF 4.00/month).
To activate or deactivate the paper bill, go to my yallo. Choose "Settings" under your profile (name at the top right) and then click on "Billing settings":
Important: You can only receive your bills by email if you have verified your email address. If a yellow message bar is shown at the top of the "Bills and Usage" page, you have not yet verified your email address. To do so, click on the button "Send validation email" on the yellow bar.