Escape email addresses with name

[sunny]

Summary

Introduce a safe way to add a name in front of an address when sending emails.

Currently

The guides' advice to do this is to do the formatting yourself:

mail(to: %("#{@user.name}" <#{@user.email}>))

Sadly this breaks if the name is Aaron "Tenderlove" Patterson or <3. Worse, it can silently let you think the email was sent, when in fact it is later swallowed by an uncomprehensive mail server.

With this change

The formatting can be handled by the email_address_with_name method:

mail(to: email_address_with_name(@user.email, @user.name))

This makes it an opt-in way to make sure that the contents are correctly escaped.

[quadule]

I've run into this issue before and have been using a similar solution involving Mail::Address.

Even better might be to allow hash arguments mapping addresses to display names for any of the headers that contain addresses. Currently, hash arguments are converted to strings and produce invalid header syntax, so changing this shouldn't break compatibility:

irb(main):001:0> ActionMailer::Base.new.mail(to: { "name@example.com" => "Display Name" }, subject: "", body: "").to_s
=> "Date: Sat, 22 Jun 2019 13:41:12 -0700\r\nTo: {\"name@example.com\"=>\"Display Name\"}\r\nMessage-ID: <2d0c9414c9031_163ccfdcc4c2a1d20d3@example.mail>\r\nMime-Version: 1.0\r\nContent-Type: text/plain;\r\n charset=UTF-8\r\nContent-Transfer-Encoding: 7bit\r\n\r\n"

[sunny]

Interesting idea! I'd love thoughts from the core team members on the preferred syntax.

[georgeclaghorn]

I think I’d prefer a helper method in ActionMailer::Base:

class ActionMailer::Base
  # ...

  private
    def named_address(name, address)
      Mail::Address.new.tap do |builder|
        builder.display_name = name
        builder.address      = address
      end.to_s
    end
end

class PostsMailer < ApplicationMailer
  def text_post(post, subscriber)
    mail to: named_address(subscriber.name, subscriber.email_address) # ...
  end
end

[sunny]

A method sounds good as well! It should also be available as a class method to handle the following:

class PostsMailer < ApplicationMailer
  default from: named_address("Acme & Co.", "acme@example.org")

  # …
end

Not sure about the name named_address though.

What about email_with_name(email, name)? Looks more like a railsy helper (number_with_delimiter, …) and informs about the order of arguments.

[simi]

I like @georgeclaghorn's idea. Is it problem to expose it as classic template view helper as well?

[georgeclaghorn]

email_address_with_name is fine.

[sunny]

Is it problem to expose it as classic template view helper as well?

I can't think of a common use-case for that for most apps, so I think it might be best to take the conservative approach of keeping it inside ActionMailer::Base.

[sunny]

@georgeclaghorn Updated using email_address_with_name! 🎉

[louim]

Hey @georgeclaghorn, could this be merged now that the changes have been applied? 🎉

[georgeclaghorn]

Sorry for neglecting this! We just need a changelog entry and then I can merge.

[sunny]

🎉 Thank you for the merge @georgeclaghorn, and to everybody that helped push this forward.