Or you can also switch the format to plain text to switch back to html. If you are looking for a workaround … always paste with ctrl+shift+v to remove any text formatting. I am so disappointed with the V7 and the lack of reactivity despite the massive complains… On the menu that loads from clicking 'settings' you should select 'Writing email' in the left column. I have sent hundred of important mails that doesn’t look well as result my messages look very unprofessional. In the top right corner of yahoo mail hover over the gear, and select 'settings' from the menu that appears.
Emclient doesn’t display the text formatting resulting of the copy/paste… You are stuck with the default font defined in the main settings … When mail arrives in gmail (or others mailbox…) the html formatting of the text is visible -> this is why you see strange fonts size for some text or paragraphs. Here the issue appears if I copy/paste texts in the message. I have the same issue and this is a critical bug coming with the V7 apparently.