Only in plain text mode, sadly. If you send an HTML message, a plain text version gets included, too, which isn't auto-wrapped. It's encoded as quoted-printable instead, which keeps lines short enough to be legal for SMTP but can be turned back into the original text by the client on the other end.

That issue basically forced me to switch from plain-text to html emails, and thence to the slippery slope of using italics and the OCD of syntax highlighting my code snippets..

I dread the slow insinuation of "the web" into email. Specifically, the need to use a rendering engine like Blink or Gecko to read an email.

Is there anything I can do to tempt you to switch back to plain-text emails?

In my defense, I still eschew html as far as possible. Even when I use html the messages are multipart, and the text versions usually are complete. I do this thing when I reply where I open the gmail menu, switch to plain text and then switch back to html. This has the effect of stripping out all styling from the message I am replying to, replacing html block quotes with conventional '>'s, and so on. That makes it easier for me to quote passages and so on.

I think of it as 99%[1] text/html with format=flowed, and if gmail ever added format=flowed to text mode[2] I'd switch back in a heartbeat.

[1] The remaining 1% of the time I'm composing something long enough that it has more in common with publishing than 1-1 communication.

[2] I wouldn't hold my breath: http://productforums.google.com/d/topic/gmail/Z42NibAOzjc/di.... More likely I'll stop using gmail one of these years..