When you wrote this: ''the guidelines for submitting to one publisher requires '''single '''line spacing within paragraphs'' …did you mean to say '''double '''line spacing? Email is by default free flow; a paragraph is phrased as a single (long) line which is dynamically re-wrapped by the viewing software. Setting lines to fixed length gets messy very quickly if the viewer's line length is shorter than the author's. Then you get messages that look like this, because the line endings embedded in the text don't line up with the natural line wraps added by the viewer. The requirement for double spacing (if that is in fact what they want) sounds very typical of typed-up submission, on paper, leaving lots of space for an editor to mark up his suggested changes. This practice doesn't fit well with email, so I'd look to see if they have any requirements specifically for email submissions. A stationery template might be suitable to allow line spacing to be set, but even there its success is very dependent on whether the various email clients etc used to view it respect such spacing instructions. You may be able to get a quick and dirty fix by copy-and-pasting your text to a word processor, deal with the layout there, and then copy and paste back into your email client.