Format HTML/Text email content to include vertical lines in replies and previous emails

Question

I'm building email functionality into an application. Most all email clients mark previous messages in the reply text with a vertical line (perhaps just the "|" character?) along the entire left hand side of the message.

Does anyone know a function/utility (preferably in python), however I can adopt from anything) that would format HTML and text content in this way? It sounds like a pretty easy problem but it's actually quite complex.

Answer 1

For plain text you can use the textwrap module. Just specify '| ' as the initial_indent and subsequent_indent arguments.

Doing it with HTML requires a different approach, since HTML is normally formatted by the browser. I guess it should be possible using CSS, but I've never done it myself, so I don't know the details.