To add lines between paragraphs, just hit the Return key for the number you want. As for the default font thing, this is a known issue and is supposedly being worked on. I can't change mine either except on a per-message basis.
My problem is REDUCING the space between paragraphs. My email format automatically puts two LARGE spaces between paragraphs instead of two NORMAL size spaces.
Of course I did all the obvious things like backspacing, etc. Back in the days before all this tech stuff did things FOR you, you could set the amount of spacing between paragraphs, etc., instead of now trying to change things to look decent. Very frustrating. Thanks anyway.
I don't know why you are getting too many lines. When I type a line and hit return I get only the next line. I have to hit return again if I want a blank line.
In my case, the line spacing displays properly when I am composing the email, but additional spacing appears to have been added when I view the email after it has been sent.
Very frustrating, and I'd like to find a resolution.