> Quoting is still a problem. Most answer above. Some below. Many nitpick in between.

One thing I've noticed on Hacker News, Slashdot, and even reddit is that if someone quotes the post they're responding to, they'll invariably post their response below it. And if they quote multiple parts of the parent post, they'll interleave their responses. I don't recall ever seeing a response where the quoted text is below it.

I've really never understood the rationale behind top-posting. It makes it much more difficult to understand the context of the response without having to jump between the original message and the response.

> Threading is easily broken. Especially if Outlook users are involved.

That's because Outlook does not follow the relevant RFCs in terms of maintaining a message through through the In-Reply-To and References headers.

> Formatting is an issue. There is no markdown or whatever for links.

Most GUI clients will make links clickable. There are also conventions such as using astericks, _underscores_, or /slashes/ for bolding, underlining, or italicizing text, but a lot of clients don't render them consistently, IME.

> Some people insist on line lengths and other stuff.

There is an RFC that adds format=flowed to the Content-Type header. Then every line that ends in a single whitespace character will be joined with the next line and wrapped at screen width instead of at the position of the CRLF characters. Clients that don't support it will still see the wrapped text.