Your emails are inheriting your site settings by default. If you go to your Theme settings, however, you'll see that you can now control the colors in your emails in a new section marked "Emails".
If you want to use different colors for your emails, you would uncheck the box next to "Inherit Default Content Background and Font Colors" in your theme, and then you'll see options to change the colors for background color, fonts, and borders.
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .