module ActionView::Helpers::UrlHelper

Email me: me@domain.com
# =>
<% end %>
Email me: me@domain.com
<%= mail_to "me@domain.com" do %>

You can use a block as well if your link target is hard to fit into the name parameter. ERB example:

# => me@domain.com
subject: "This is an example email"
mail_to "me@domain.com", cc: "ccaddress@domain.com",

# => My email
mail_to "me@domain.com", "My email"

# => me@domain.com
mail_to "me@domain.com"
==== Examples

install the +actionview-encoded_mail_to+ gem.
in order to hinder email harvesters. To take advantage of these options,
Prior to Rails 4.0, +mail_to+ provided options for encoding the address
==== Obfuscation

* :reply_to - Preset the +Reply-To+ field of the email.
* :bcc - Blind Carbon Copy additional recipients on the email.
* :cc - Carbon Copy additional recipients on the email.
* :body - Preset the body of the email.
* :subject - Preset the subject line of the email.
==== Options

passing special keys to +html_options+.
+mail_to+ has several methods for customizing the email itself by

HTML attributes for the link can be passed in +html_options+.
also used as the name of the link unless +name+ is specified. Additional
Creates a mailto link tag to the specified +email_address+, which is

def mail_to(email_address, name = nil, html_options = {}, &block)
  html_options, name = name, nil if name.is_a?(Hash)
  html_options = (html_options || {}).stringify_keys
  extras = %w{ cc bcc body subject reply_to }.map! { |item|
    option = html_options.delete(item).presence || next
    "#{item.dasherize}=#{ERB::Util.url_encode(option)}"
  }.compact
  extras = extras.empty? ? "" : "?" + extras.join("&")
  encoded_email_address = ERB::Util.url_encode(email_address).gsub("%40", "@")
  html_options["href"] = "mailto:#{encoded_email_address}#{extras}"
  content_tag("a", name || email_address, html_options, &block)
end