Addition to Post via Email instructions
Under Journal entry options, it states that Most journal specific features can be set via "lj-headers" in the body of your message.
One of the few settings that can't be changed by with a lj-header is the "don't auto-format" option, which is particularly relevant to people using email clients that automatically insert linebreaks at the ends of lines. The solution is to use <lj-raw> tags, but this isn't obvious unless the user is knowledgeable about the lj-specific tags. Might it make sense to add a paragraph like this to this section?:
The don't auto-format feature cannot be set via a lj-header. If you'd like to keep your entry from automatically formatted, place the body of your post between <lj-raw> </lj-raw> tags.