Rails uses plain/text as the default content_type for sending email, you can change it to text/html that email clients can display html formatted email.
But not all the email clients support html format well, we should make our sent emails support both plain text and html format for different email clients.
text/plain:
By default Rails sending an email with plain/text content_type, for example
# app/models/notifier.rb def send_email(email) subject email.subject from email.from recipients email.recipients sent_on Time.now body :email => email end # app/views/notifier/send_email.html.erb Welcome to here: <%= link_to @email.url, @email.url %>
The sent email is a plain text email
Date: Tue, 9 Aug 2011 16:38:07 +0800 From: VeeraaWP <veeraa@wordpress.com> To: some-user@gmail.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Welcome: <a href="https://veerasundaravel.wordpress.com">http://veerasundaravel.wordpress.com</a>
The link url is just displayed as a plain text because of the email content_type.
text/html:
If we want the email clients to display link url as html format, we should change the content_type to text/html.
# app/models/notifier.rb def send_email(email) subject email.subject from email.from recipients email.recipients sent_on Time.now content_type "text/html" body :email => email end # app/views/notifier/send_email.html.erb Welcome to here: <%= link_to @email.url, @email.url %>
Now the sent email is a html formatted email
Date: Tue, 9 Aug 2011 16:38:07 +0800 From: VeeraaWP <veeraa@wordpress.com> To: some-user@gmail.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Welcome: <a href="https://veerasundaravel.wordpress.com">http://veerasundaravel.wordpress.com</a>
Now the email client can display the link url correctly with html format.
multipart/alternative:
But we can’t promise that all the email clients support the html format and some users will set the email client to display plain text email instead of html formatted email. How should we do?
We should use multipart/alternative as email content_type to support both text/plain and text/html emails.
# app/models/notifier.rb def send_email(email) subject email.subject from email.from recipients email.recipients sent_on Time.now content_type "multipart/alternative" part :content_type => "text/html", :body => render_message("send_email_html", :email => email) part "text/plain" do |p| p.body = render_message("send_email_plain", :email => email) p.transfer_encoding = "base64" end end # app/views/notifier/send_email_html.erb # app/views/notifier/send_email_plain.erb
As you see, we can set the email content_type to multipart/alternative, then define content_type text/html render the file app/views/notifier/send_email_html.erb and content_type text/plain render the file app/views/notifier/send_email_plain.erb. So the sent email is as follows
Date: Tue, 9 Aug 2011 16:17:35 +0800 From: VeeraaWP <veeraa@wordpress.com> To: some-user@gmail.com Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=mimepart_4c5a739f40ca1_967c1a0d6123 --mimepart_4c5a739f40ca1_967c1a0d6123 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: Quoted-printable Content-Disposition: inline Welcome: <a href="https://veerasundaravel.wordpress.com">http://veerasundaravel.wordpress.com</a> --mimepart_4c5a739f40ca1_967c1a0d6123 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: Quoted-printable Content-Disposition: inline Welcome: <a href="https://veerasundaravel.wordpress.com">http://veerasundaravel.wordpress.com</a> --mimepart_4c5a739f40ca1_967c1a0d6123--
As you see, the content_type of email is multipart/alternative now, and the body of email is divided into two parts, one is for text/plain, the other is for text/html. So email clients can decide which format of email to display.
Convention:
It’s cool, but can the codes be simpler? Of course, there is a convention to simplifier the multipart/alternative content_type
def send_email(email) subject email.subject from email.from recipients email.recipients sent_on Time.now body :email => email end # app/views/notifier/send_email.text.plain.erb # app/views/notifier/send_email.text.html.erb
Please note the file extensions for notifier send_email method, one is .text.plain.erb, the other is .text.html.erb, they are the email views for text/plain and text/html according to their names. ActionMailer will detect the file extension, if .text.plain and .text.html exist, the content_type of email will be set to multipart/alternative automatically.
In rails3: the mail view file names should be send_email.html.erb and send_email.text.erb
Related articles:
Rails, email and multipart/alternative (olddognewtricks.co.uk)
Rails Best Practices (rails-bestpractices.com)