<% if @email.respond_to?(:smtp_envelope_from) && Array(@email.from) != Array(@email.smtp_envelope_from) %>
SMTP-From:
<%= @email.smtp_envelope_from %>
<% end %> <% if @email.respond_to?(:smtp_envelope_to) && @email.to != @email.smtp_envelope_to %>
SMTP-To:
<%= @email.smtp_envelope_to %>
<% end %>
From:
<%= @email.header['from'] %>
<% if @email.reply_to %>
Reply-To:
<%= @email.header['reply-to'] %>
<% end %>
To:
<%= @email.header['to'] %>
<% if @email.cc %>
CC:
<%= @email.header['cc'] %>
<% end %> <% if @email.bcc %>
BCC:
<%= @email.header['bcc'] %>
<% end %>
Date:
<%= Time.current.rfc2822 %>
Subject:
<%= @email.subject %>
<% unless @email.attachments.nil? || @email.attachments.empty? %>
Attachments:
<% @email.attachments.each do |a| %> <% filename = a.respond_to?(:original_filename) ? a.original_filename : a.filename %> <%= link_to filename, "data:application/octet-stream;charset=utf-8;base64,#{Base64.encode64(a.body.to_s)}", download: filename %> <% end %>
<% end %>
Format:
<% if @email.html_part && @email.text_part %>
<% elsif @part %>
<%= @part.mime_type == 'text/html' ? 'HTML email' : 'plain-text email' %>
<% else %>
<% end %> <% if I18n.available_locales.count > 1 %>
Locale:
<% end %> <% unless @email.header_fields.nil? || @email.header_fields.empty? %>
Headers:
Show all headers <% @email.header_fields.each do |field| %> <% end %>
<%= field.name %>: <%= field.value %>
<% end %>
EML File:
<%= link_to "Download", action: :download %>
<% if @part && @part.mime_type %> <% else %>

You are trying to preview an email that does not have any content. This is probably because the mail method has not been called in <%= @preview.preview_name %>#<%= @email_action %>.

<% end %>