To secure your email account, the first step is to know the vulnerabilities of your email service. Read the TOS of the email service provider, and make sure that your messages are encrypted and protected from brute-force attacks. It is also vital to have alternate contact information if you don't want your email account to be compromised. Keep a backup of your passwords and other important information. Once you've updated the password, you're ready to secure your emails.

See also - https://amirarticles.com/how-to-secure-your-email-address/