Annoyance. Last email viewed stays loaded

When I switch from one account to another or even between folders the last email viewed is still displayed. For example say I viewed Trash folder and read an email there, if I then click on Inbox, and there are no emails in the inbox, the Trash email is still displayed. I can't clear the screen, even when switching between accounts. This could possibly be embarrassing if I'm switching between personal and work email. Is there any way to either clear the email from view or to force Mail to display a blank page, or at least to change the folder to the empty one?