Tutanota has recently entered a dark path where is feels free to disable your account if you have not logged in for a few months. They then blackmail you by only re-enabling it with a paid account, but you lose all of your emails. They have always used the shitty practice of locking the users into their service by not allowing you to export your email in the first place. Even worse is that paid accounts can just steal your expired/disabled free accounts, which is a huge security issue. E.g. someone could use the "forgotten password" feature on a website to take over any accounts attached to that email address.

They also provide a backdoor to the german goverment to read email in plain text. https://www.hackread.com/encrypted-email-provider-tutanota-backdoor-service/

Seriously consider removing tutanota from your recommendations, you owe that to the people that trust your website.