1. Message Width: set the width for the content area. This is used when the device has a screen larger than that width. You can think of it as a "max" width for that content area. On small devices, it will be ignored.
2. Background Color: the default background color for the message. You will be able to override it at the row, column, and content block level when settings properties for those elements.
3. Message Background Color: the default background color for the content area, which is the area for which you set the Message Width above.
4. Font: the default font family that all content elements in the message will inherit. Of course, you can overwrite this selection at the content block level.
5. Link Color: the default link color that all links will inherit, unless you overwrite it for individual elements.