Premailex - Inline email styling made simple

danschultzer

Pow Core Team

I needed something like premailer for rails, and after searching, I decided to make an easy-to-use library to handle inline styles and convert to text for emails. It’s straightforward, and it handles external stylesheets too!

Here’s an example with Bamboo using a Phoenix template:

def welcome_email do
  new_email
  |> subject("Email subject")
  |> to("test@example.com")
  |> from("test@example.com")
  |> put_text_layout(false)
  |> render("email.html")
  |> premail()
end

defp premail(email) do
  html = Premailex.to_inline_css(email.html_body)
  text = Premailex.to_text(email.html_body)

  email
  |> html_body(html)
  |> text_body(text)
end

I hope some of you’ll find this library useful!

https://github.com/danschultzer/premailex

4 comments

#library #emails

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2026-10-29 04:41:19 UTC

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ragamuf

Much appreciated.

Post #1

danschultzer

Pow Core Team

Premailex v1.0!

Reached a huge milestone that finally got Premailex to a place I wanted it to be since first release, mainly:

CSS parsing is done with binary parsing rather than regular expression
Zero dependencies with a naive :xmerl fallback for HTML parsing if none of LazyHTML, Floki, Meeseeks are available

A bunch of other changes have gone into it and applying inline styles is now typically 30x+ faster. Many more changes in the changelog.

Post #2

mudasobwa

Creator of Cure

As a person who literally hates receiving emails in HTML, I am to suggest you to take a look at marcli which can be used to produce kinda formatted text messages out of a markdown template.

Actually, a support for markdown templates for HTML body might be a good addition to the library, too.

Post #3

danschultzer

Pow Core Team

Yeah, HTML emails should always have plaintext alternatives. Premailex converts HTML to plaintext so you don’t have to maintain two versions yourself.

marcli looks cool, but not sure how markdown templates would fit in Premailex. Premailex is for processing already rendered HTML emails to ensure it can render correctly in email clients as well as producing plaintext alternative.

Over the years I have attempted different versions of mail templates in Phoenix and HTML is the simplest. Most recently it’s just been something like this:

defmodule MyAppWeb.Mail do
  import Swoosh.Email

  alias MyAppWeb.{Layouts, MailHTML}

  defp send_sample_email(user) do
    title = "Sample email"

    assigns =
      %{
        title: title,
        user: user
      }

    html = render_email(:sample, assigns)
    text = Premailex.to_text(html)

    new()
    |> from({"MyApp", "no-reply@notifications.example.com"})
    |> reply_to({"MyApp", "hello@example.com"})
    |> to(user.email)
    |> subject(title)
    |> html_body(html)
    |> text_body(text)
    |> deliver(:sample)
  end

  # ...

  defp render_email(type, assigns) do
    inner = Phoenix.Template.render(MailHTML, "#{type}", "html", assigns)
    root_assigns = assigns |> Map.put(:inner_content, inner) |> Map.delete(:layout)

    Layouts
    |> Phoenix.Template.render("mail", "html", root_assigns)
    |> Phoenix.HTML.Engine.encode_to_iodata!()
    |> IO.iodata_to_binary()
    |> Premailex.to_inline_css()
  end

  def deliver(mail, type) do
    mail
    |> put_provider_options()
    |> Mailer.deliver()
  end
end

defmodule MyAppWeb.MailHTML do
  @moduledoc false
  use MyAppWeb, :html

  embed_templates "mail_html/*"
end

With the mail.html.heex root template under components/layouts and everything else under mailers/. The root template has all styling in the style tag in <head>.

Markdown → HTML email would probably fit in this setup as well with Premailex used to ensure the rendered HTML has the applied inline styles.

Post #4

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