Most know where the Delete key lives, and use it frequently. Many people have their email reading window set at 65 characters as the maximum line length. This is difficult to read. Everybody has a right to their opinion. Good luck with this one.
Many people are almost as impatient when checking email as when surfing.
If you don't make it easy for those who receive your message to read it, it may be trashed. Most newsletters use this line length, some even less. Also be hesitant to quote the entire message below your reply. If I can't remember easily, I have to go hunting for what I said, which takes time. This is particularly true when the reply is to a message sent out three or four days back.