For the best HTML e-mail delivery results, CSS should be inline. This is a huge pain and a simple newsletter becomes un-managable very quickly. This gem is a solution.

• CSS styles are converted to inline style attributes
  • Checks style and link[rel=stylesheet] tags and preserves existing inline attributes
• Relative paths are converted to absolute paths
  • Checks links in href, src and CSS url('')
• CSS properties are checked against e-mail client capabilities
  • Based on the Email Standards Project's guides
• A plain text version is created (optional)

gem install premailer

require 'premailer'

premailer = Premailer.new('http://example.com/myfile.html', warn_level: Premailer::Warnings::SAFE)

# Write the plain-text output (must come before to_inline_css)
File.write "output.txt", premailer.to_plain_text

# Write the HTML output
File.write "output.html", premailer.to_inline_css

# Output any CSS warnings
premailer.warnings.each do |w|
  puts "#{w[:message]} (#{w[:level]}) may not render properly in #{w[:clients]}"
end

1. nokogiri (default)
2. nokogiri_fast (20x speed, more memory)
3. nokogumbo

(hpricot adapter removed, use ~>1.9.0 version if you need it)

Picking an adapter:

Premailer::Adapter.use = :nokogiri_fast

See .github/workflows/actions.yml for which ruby versions are tested. JRuby support is close, contributors are welcome.

Premailer looks for a few CSS attributes that make working with tables a bit easier.

Each of these CSS declarations will be copied to appropriate element's attribute.

For example

table { -premailer-cellspacing: 5; -premailer-width: 500; }

will result in

<table cellspacing='5' width='500'>

Premailer can generate a plain text version of your HTML. Links and images will be inlined.

For example

<a href="https://example.com" >
  <img src="https://github.com/premailer.png" alt="Premailer Logo" />
</a>

will become

Premailer Logo ( https://example.com )

To ignore/omit a section of HTML content from the plain text version, wrap it with the following comments.

<!-- start text/html -->
<p>This will be omitted from the plain text version.</p>
<p>
  This is extremely helpful for <strong>removing email headers and footers</strong>
  that aren't needed in the text version.
</p>
<!-- end text/html -->

For example:

Premailer.new(
  html, # html as string
  with_html_string: true,
  drop_unmergeable_css_rules: true
)

available options

Contributions are most welcome. Premailer was rotting away in a private SVN repository for too long and could use some TLC. Fork and patch to your heart's content. Please don't increment the version numbers.

A few areas that are particularly in need of love:

• Improved test coverage
• Move un-repeated background images defined in CSS for Outlook

Thanks to all the wonderful contributors for their updates.

Thanks to Greenhood + Company for sponsoring some of the 1.5.6 updates, and to Campaign Monitor for supporting the web interface.

The source code can be found on GitHub.

Copyright by Alex Dunae (dunae.ca, e-mail 'code' at the same domain), 2007-2017. See LICENSE.md for license details.