Disable vertical quote bar? Mail.app's vertical bar formatting of replies is usually useful.  I have one annoying case that comes up very frequently for me that I have been trying to find a solution for.  I am a Python programmer and am on mailing lists that include Python code snippets regularly.  The problem is that Python command line application uses &gt;&gt;&gt; as its prompt.  This triggers the quote formatting behavior incorrectly.  For example, the following email snippet is formatted incorrectly (IMO).

The code is useless, just to show the idea

&gt;&gt;&gt; a = [1,2,3]
&gt;&gt;&gt; a.append(4)
&gt;&gt;&gt; a.sort()
&gt;&gt;&gt; c = max(a) + 1

I would be very happy to have

&gt;&gt;&gt; [1,2,3].append(4)::sort()::max() +1


The result in Mail.app is:



Does anyone know of a way to disable the quote bar behavior altogether?

source email: https://mail.python.org/pipermail/python-ideas/2019-February/055374.html
You could turn off quoting. 
mail > preferences 
see responding section.