The recipient client's limitations shouldn't limit me as a sender. If I want to include a long code sample, or some concrete poetry, gmail shouldn't step on my toes. I don't mind the current behavior being the default, but it should be settable.
That's fine, just as long as you also recognize the recipient's ability to configure away your code sample and poetic white space entirely.
Configurable pattern heuristics to help me, as a recipient, optimally render text would be much more welcome than any capability that could be provided to me as a sender.
I can send you a very long message, in a paragraph, like this. It has a lot of words, and display is determined by the software running on the display device. Immediately afterwards I can include some code:
// Do a thing. This a pretty boring example, but it's here to
// illustrate a point. I've hard wrapped it to fit at some
// arbitrary length
var foo = 'bar'
