In order to protect your email communications we recommend you sign up for an encrypted email service. Although the largest free email service providers do use encryption to prevent prying eyes from looking at your messages while they are in transit, these same providers scan the contents of your email messages to build a profile of you and target advertising to you. They will also turn over details to law enforcement agencies if they receive court orders to do so.
Proton Mail and Tutanota both have free plans which let you easily upgrade to a paid plan later. Both of these are headquartered in Europe, Proton Mail in Switzerland and Tutanota in Germany.
+ ‘How Encryption Works – and How It Can Be Bypassed’ [Video], Wall Street Journal