You can protect your Google e-mail account by enabling two-step verification, which includes features such as phone verification, authenticator app, back-up codes, and security keys.
Hotmail/Outlook allows you to secure your email by using two-step verification. Visit this link to find out more.
iCloud/Me/Mac now gives you the ability you to secure your email with two-step verification. Visit this link to find out more.
Yahoo! Mail allows you to secure your email by using two-step authentication. Visit this link to find out more.
Warning: We do not recommend Yahoo! email due to a change in policy that allows Yahoo to re-distribute your user accounts if they become inactive, or due to the fact that a recent data breach has leaked data from over one billion e-mail accounts. This is a considerable security risk. Please read more at Naked Security or CNN.