I view all emails in plain text by default. However some emails only show content in HTML view. I would love to be able to toggle between these views quickly (for one email) without having to go to the "View" menu and change the setting for the whole application. I would love to have a button that can be added to the email header via the customization or to at least have it in the context menu of the email content. (There is an add-on that tries to provide exactly this functionality but doesn't work properly. I assume that is because thunderbird considers this an application wide setting right now.) Thunderbird