Markdown emails with syntax highlighting on each <pre> block

mark-email.rb

#!/usr/bin/env ruby
# encoding: UTF-8

require 'nokogiri'
require 'open3'

html = Open3.popen2('redcarpet') do |stdin, stdout|
  stdin.write(STDIN.read)
  stdin.close

  stdout.read
end

doc = Nokogiri::HTML(html)

doc.xpath("//p").each do |p|
  p['style'] = %(font-family: Calibri, Helvetica, Arial, sans-serif)
end

doc.xpath("//code").each do |code|
  code['style'] = %(background: #eee; color: #d14; ) +
    %(font-family: Consolas, 'Courier New', monospace)
end

doc.xpath("//blockquote").each do |blockquote|
  blockquote["type"] = "cite"
end

doc.xpath("//pre[@lang]").each do |pre|
  lang = pre.attr('lang')
  Open3.popen2("pygmentize -l #{lang} -f html -O noclasses -O style=pastie") do |stdin, stdout|
    stdin.write(pre.inner_text)
    stdin.close

    pre.replace(stdout.read)
  end
end

puts doc.to_html

Useful for creating rich HTML emails in Thunderbird by Insert > HTML