You ask for two contradictory things. To use different fonts, you will need to use HTML formatting. But one of the characteristics of this is that it flows text to fit the display, both at the sender and at the receiver. Carriage returns signify paragraph breaks, not line ends, so can't be used to force the line length. And if you somehow do set fixed line lengths, it's possible that you will create messages that don't fit into the recipient's display. Perhaps you could give some more concrete examples of what you want to do. It may be that tables would work for you, or maybe Stationery templates that set margins. Do you use a word processor? How do you force line length there? In my experience, you don't try; it sorts that out to fit the chosen type size to the paper, accommodating to the margins. The fact that a word processor ultimately aims for a printed document, on paper, is the crucial difference. Email is essentially a purely electronic communications medium and paper size is not one of its considerations.