How to Create Email with CSS and Images from Rails

How do I create email with css and images from Rails?

Assuming you know how to send normal plain-text emails from Rails using ActionMailer, to get HTML emails working you need to set a content type for your email.

For example, your notifer might look like this:

class MyMailer < ActionMailer::Base
  def signup_notification(recipient)
    recipients   recipient.email_address_with_name
    subject      "New account information"
    from         "system@example.com"
    body         :user => recipient
    content_type "text/html"
  end
end

Note the content_type "text/html" line. This tells ActionMailer to send an email with a content type of text/html instead of the default text/plain.

Next you have to make your mailer views output HTML. For example, your view file app/views/my_mailer/signup_notification.html.erb might look like the following:

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
   "http://www.w3.org/TR/html4/loose.dtd">

<html lang="en">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <style type="text/css" media="screen">
      h3 { color: #f00; }
      ul { list-style: none; }
    </style>
</head>
<body>
  <h3>Your account signup details are below</h3>
  <ul>
    <li>Name: <%= @user.name %></li>
    <li>Login: <%= @user.login %></li>
    <li>E-mail: <%= @user.email_address %></li>
  </ul>
</body>
</html>

As you can see the HTML view can include a <style> tag to define basic styles. Not all HTML and CSS is supported, especially across all mail clients, but you should definitely have sufficient formatting control over text styles.

Embedding images is a bit tricker if you plan to display attached emails. If you are simply including emails from external sites, you can use an <img /> tag as you usually would in HTML. However, many mail clients will block these images from being displayed until the user authorises it. If you need to display attached images, the Rails plug-in Inline Attachments might be worth a look.

For more information on Rails mailing support, the ActionMailer documentation is a great resource

CSS Images in Email With Rails 3

In response to my other answer, @Kevin wrote:

Thanks for the answer, I did think of doing something like that but I
don't think it's possible with the way I have it setup. The mailer
call is happening in a after_create call in a model rather than in a
controller so I don't think I have access to the request object as you
mentioned (or am I mistaken). I do have this in my mailer initializer:
ActionMailer::Base.default_url_options[:host] = "localhost:3000" Can I
somehow use that hos parameter in my mailer to make it work?

The answer is yes. All rails url-construction helpers should use these defualt_url_options. In addition to setting the :host, you should also force it to use absolute urls by settings this option:

ActionMailer::Base.default_url_options[:only_path] = false

Also, set the asset host like this:

config.action_mailer.asset_host = 'http://localhost:3000'

Then just use the image_path helper instead of hand-writing the url, like this:

<style type="text/css">
body {
    background: url(<%= image_path('mainbg_repeat.jpg') %>) top repeat-x #cfcfcf;
}
</style>

NOTE: Setting default_url_options directly like that is deprecated. Here's the new way to do it:

config.action_mailer.default_url_options = {
    :host => 'localhost:3000',
    :only_path => false
}

rails email not displaying images from css

CSS for HTML emails must be inline, and many email clients cannot display all CSS entities.

MailChimp has a tool to help bring your CSS inline - http://beaker.mailchimp.com/inline-css

And Campaign Monitor has this great list of CSS elements and where they are supported - http://www.campaignmonitor.com/css/

Image/CSS in Mailer in Rails is not applied only in Gmail

I think you need to define your image as an attachment in your mailer. E.g. I have a mailer in app/mailers/customer_mailer.rb that has a method verification_confirmation. In this method I have the following line:

attachments.inline['logo.png'] = File.read(Rails.root.join("app/assets/images/logo.png"))

Now, in the view for this email (i.e. app/views/customer_mailer/verification_confirmation.html.erb I can now embed the image like this:

<%= image_tag attachments['logo.png'].url, style: "width: 15vw; min-width: 200px;" %>

How to send email with image background without attach this image as a file for download?

Skip asset pipeline for static images to work in your emailer, you should put them in:

Rails.root + 'public/images'

Then in our emailer you should use css with full url to the image:

 background-image:url('http://yoursite.com/public/images/background.jpg');

I would recommend use style tag in your mailer and just add the class like this:

<style>
  .my-fancy-background {
    background-image: url('http://yoursite.com/public/images/bg-email.jpg');
    background-position: top center;
    background-repeat: no-repeat;
    background-color: transparent;
  }
</style>
<div class="my-fancy-background">
  Here is my email div with some fancy background  
</div>

But if you still want helper method, you might also need to set this in application.rb

config.action_mailer.asset_host = 'http://example.com/public/' 
# use public url of your app where your static images can be served from.

UPDATE

As per comment by gwally, this may not be supported in Outlook so if you care that this will be supported for Outlook, you might wanna have a look here

How to send HTML email with styles in rails

It's not a best pratice to add file with your CSS in an email. You need define your CSS inline in your email.

About Asset, it's better to host it in your website. You can link it in your email. Your email is lighter with this technique.