Plain Text means plain text – no formatting options
When CBS Interactive decided to move to Google Enterprise Apps, it took me a frustratingly longer time than it should have to figure out how to add the graphical element to my signature. Allow me to save you some frustration by showing how to set it up.
Have the right view
The most important thing is to have the right email view. As you can see in Figure B, I am using the Plain Text version of the Gmail email composing tool. Note the lack of formatting options (red arrow).