"With Proton Mail, you can snooze your emails and be reminded about them at a more convenient time. This ensures you’ll never forget or miss an email, as it will reappear in your inbox when you’re ready to take action.

"Note that you can currently only snooze emails from the Proton Mail beta web app.

“Anyone can snooze emails for predefined times. If you’re on a paid plan, you can also set a custom snooze time.”