redmine/app/views/mailer/message_posted.html.erb

<h1><%= @message.board.project.name %> - <%= @message.board.name %>: <%= link_to(@message.subject, @message_url) %></h1>
<em><%= @message.author %></em>

<%= textilizable(@message, :content, :only_path => false) %>

<% if @message.attachments.any? -%>
<fieldset class="attachments"><legend><%= l(:label_attachment_plural) %></legend>
<% @message.attachments.each do |attachment| -%>
  <%= link_to_attachment attachment, :download => true, :only_path => false %> (<%= number_to_human_size(attachment.filesize) %>)<br />
<% end -%>
</fieldset>
<% end -%>