Back in January this year, the company's homepage stated: "No personal information is required to create your secure email account. By default, we do not keep any IP logs which can be linked to your anonymous email account. Your privacy comes first."
Today that boast has been replaced with a mealy-mouthed version: "ProtonMail is email that respects privacy and puts people (not advertisers) first. Your data belongs to you, and our encryption ensures that. We also provide an anonymous email gateway."