I have heard from many victims of stalking over the years that their emails were being hacked. They would use other computers, the library, anything they could, in order to send private emails without their stalker reading them and/or using them to locate their victim.
Proton Mail is a highly encrypted email service. https://protonmail.com
Is ProtonMail really safe?
ProtonMail is the world’s largest secure email service. It offers end-to-end encryption and lots of other great security features to keep your communications private. Even the company hosting your emails has no way of reading them, so you can rest assured that they can’t be read by third parties either.